I'm replacing my solid roller cam in my 508. 4.250 stroke 4.360 bore, compression ratio 12.11 Edelbrock RPM heads Intakes flow 308 CFM, M1 4500 flange, 950/4150 Ultra XP., 2" pirimary tube TTI headers, 727 with 8" PTC converter flashes 56-5800RPM, 4.56 gear, 14 x 32 tire, weight with me in the car is 3378 lbs. 71 Cuda Race only. I spoke to 3 cam manufacturers. All 3 recommended similar cams.

#1 310/318 adv. 279/287@.050 .713 lift at the valve with my current rocker 1.67 ratio 109 lobe separation 31* between advertised duration and @.050
#2 314/316 adv. 278/287@.050 .708 lift at the valve with my current rocker 1.67 ratio 106 lobe separation 36* between advertised duration and @.050
#3 308/315 adv. 308/275@.050 .733 lift at the valve with my current rocker 1.67 ratio 108 lobe separation 33* between advertised duration and @.050
My current cam is 306/273@ .050 .694 lift at the valve with my current rocker 1.67 ratio 108 lobe separation 33* between advertised duration and @.050

With the current cam the 508 made 645 HP @ 6000 RPM and 643 Tq. at 4900 RPM and went as fast as 10.03/132 through the exhaust.
My question's are what would be recommended for the Lobe Separation based on the small cylinder head, the weight of the car and the converter stall and any other variable that I may not be thinking about?
My second question is how does the ramp speed affect the way the cam act's. I think the slower ramp is a little easier on springs etc.. Is there a good reason HP/tq. wise to want the faster ramp speed?
This is a footbrake bracket car.
Thanks

Basing any comparisons off advertised duration can be misleading. There isn't really a standard, so some cam companies can define it differently. This information should be stated somewhere in the camshafts information.

Most when camparing camshaft profiles will look at the duration @0.200" and 0.050", along with the lobe lift. Generally speaking, the faster you can get the intake valve open, the more power you'll make, provided you can control its motion.

As for lobe separation, I would imagine it would need to be on the tighter side, but I'll leave that for someone whom is more knowledgable on your style of engine.

I wouldn't use any of those cams suggested on your motor
Way more duration @ .050 than I would like, are any of those companies Bullett or Ultra Dyne?
I have built and raced a street car with similar parts with less compression and more rocker arm ratio and net lift at the valves, that cam was 260 @ .050 with .420 lobe lift on the intakes and 266 @ .050 with .409 lobe lift on the exhaust lobes ground on a 108 LSA installed at 1.06 ILC with Harland Sharp 1.65 ratio roller rockers that had between .695 and .720 net lift at the retainers with checking springs, that cam flat work very well
I did end up using the Crower solid roller lifters with the .820 wheels in them after breaking two Mopar Brand solid roller lifter wheels in half that had the smaller .750 diameter roller wheels in them
Your car may be as fast or faster than my old pump gas Duster that weighed 3450 Lbs. with me in it, best of 10.09 at 127+ MPH through the complete exhaust system with the air cleaner on with the Eddy CNC ported RPM heads
Me thinks they are recommending a BB Chevy type cam for you instead of one for your motor with your heads
IHTHs

Cab, it was Bullet, Lunati and comp cams in that order. Existing cam is also comp cams.

Just to give a few ideas. With the duration cams given, you need to spin the engine pretty fast, so I am not sure the cylinder head flow will support the kinds of engine RPM the cams are ground for. and the 2 inch headers would seem a little small for that size engine.
I am a big proponent of using engine software to design my engine combinations, taking time to put good exact numbers into the programs, before talking to the cam companies, and then putting their recommendations through the program as well, a few bucks on computer software is a lot cheaper than several cams and the cost to replace them. I really liked the camshaft recommended by Mike Jones " cam king", it was a little smaller on duration than most cams the other companies wanted me to use, and it gave me the best ET and MPH the car ever had. 540 with two AFB, NSS car 3200 lbs I went 6.03 @ 114mph in the 1/8, ran a string of 9.70's in high humidity and 90 degree heat this summer in the 1/4 as well.

It’s a 508 with std port Ede heads and a std port intake.

It’s not going to peak at a very high rpm no matter how big the cam is.

The main hurdle with those heads is coming up with enough installed height to fit a spring big enough to allow a cam that’s fast enough/big enough to make much of a difference than what’s posted, or the current cam.
The other issue is with the “big springs”, the integrity of the fairly small rocker stands would be a concern for me.

My guess is, there wouldn’t be too much difference in power from different cams with similar lift and duration, if they are all designed to operate with what is a “typical” spring used on those heads.

Yep, best power is changing the heads! Cam change won't net much if anything.

Number two. Should run strong

This raises the question, will the block live with a substantial power increase? If you definately are going after more power with an rb(i assume) shortblock, i would be tempted to try a tunnelram, e85 or methanol, mechanical injection and maybe wrap all three into one package. I ran a mechanical fuel injection and used a carb with no boosters or fuel in it for a throttle body. Worked great. Picked up .25 et and 3 to 4 mph over a gas dominater. Going this way should be easier on the shortblock than bigger heads. Most of the gain will be torque in the same rpm range. If you have interest in this route pm me and i can help you avoid the pitfalls.

Thanks to everyone that responded to my questions. The reason I'm looking at a cam change is due to some damage on a couple of cam lobes. I originally picked this cam for a 3.750 stroke 440 and it worked very well in that but at a much higher RPM then in the 4.250 stroke 508.I'm not looking for a big HP gain however if picking a cam that's better suited to my combination nets me additional HP or no HP but maybe it drops off less drastically above peak it's a win. I just don't want to go backwards and lose HP or drastically change the way the car works. I realize that my heads are a cork and replacing them with a Max wedge style port would be a big gain but that's not in my budget. An aftermarket block is also not in the budget so I need to stay within the constraints of the factory block. I split a block in the past but it was due to detonation. My fault and I'm very conscious of it now so it doesn't happen again at least not that way. LOL. I recently spoke with Dwayne Porter and he is very helpful and has a great deal of knowledge regarding combinations similar to mine as do many of you. He suggested a couple of things and I will likely be making a purchase through him but first I have a little bit of homework to do regarding existing springs and valve pockets etc..