I am building a new bullet for my 68 cuda, heres what I have

71 340 block .020 over forged mopar 4inch stroke crank. I will run K1 or SCAT I beam rods and pistons to get me around 10.5-11 to 1 compression.

Comp XE 268 cam 1.7 mopar performance roller rockers

770 Holley street avenger OR 850 T-quad

TTI headers, 2.25 dual ex under rear bumper no mufflers but does have a crosover pipe.

Aluminum magnum heads, lightly ported, mostly opened PR pinch and deshrouded the chamber a little around the valves.

ARP studs

2200 stall LU converter 904 with low 1st 2nd extra clutches TF2 shift kit set for max performance but still automatic shift.

2.76 8.75 clutch type SG

235 55 17 michilin tires.

3077 LBS full of fuel no driver.

I want lots of tq because of the high gear ratio but not so much I can't hook with those tires. I have 3 intakes sitting around to pick from

Tourquer II, M1 single plane, and an RPM airgap.

Witch intake should I use and how much power can I expect, TQ and HP?

RPM air gap all the way. Using a single plane with the small cam will only result in lost TQ without a gain up top. I'm not familiar with the heads so I only have a guess,450ftlbs @ 3500rpm 380ish HP @5000 rpm.Well ported heads and the correct cam will help everwhere. Stroker small blocks are hard on tires,street tires are useless even on the interstate.

I have seen several articles about these heads, usually around 220 OOTB and close to 300 (depending on the flow bench and the guy doin the grindin)fully ported, I would conservatively guess mine around 250-260 cfm @.500.

Any min CSA measurements on those heads? Most stock replacement heads really limit the upper RPMS even on less CID,so anything to get the heads right for the combo is critical.

Air-Gap intake, but you might want to try the others also.
your cam seems a bit small to me.

I had a similar duration cam in my 402 stroker I had and it was just a hair rougher than I like, with the extra cubes I think I will like this one, plus the 1.7 rockers should help it get some valve lift quick to access the higher flow, kinda like how the engine masters guys run there cams/rockers, fast lift lobes and high ratio rockers but I know it will be a little less duration than they run. They typically make peak HP around 6500 I am shooting for 6000 so I can have a little more on the low end.

my

The Air gap will make more average torque but will probably limit top end power over 5000 vs the M1, (especially with that small cam) a 4" arm doesn't really need the dual plane to generate port velocity and at higher piston speeds the AIR Gap (which side by side looks to be internally identical to the std RPM). You my have too much static and now dynamic compression for a practical street car in the summer with marginal gas...especially if you went with the RPM intake with the XE grind with it's fast ramps....too high velocity at too low an RPM/piston speed can limit power up top....what you may is what turns into flow restrictions in series. If I couldn't come up with the optimum solution, I'd go bigger runner/smaller cam or vice versa to attempt to overlap the torque peaks because restrictions in series can really handicap a combo.

On strokers I tend to run about 6-10 degrees larger on the intake than a lot of people but phase it in earlier by +4-6 degrees to achieve the same Intake closing timing after BDC, it just makes more power and torque with no downside I could ever find With a smaller port (relative to the 340" motor the port was designed for) and that long stroke you want to give the valve more of a "head start". If you dig into what a lot of the Engine masters guys do (Kaase/ Bischoff etc), this is one of their key tuning tricks on the big stoke motor combinations....if you just look at the cam specs they seem to big to make massive torque down low...but they do.

I also like big cross sectional dual plane intakes, if they would cast a RPM about 15% larger internally (Particularly the 4 plenum passages that feed each 2 port branch) it would be an even more awesome piece for strokers.

The M1 has great runners, vey much a modernized Strip dominator....if you have the headflow for it and the RPM powerband to use it it should make more power above the torque peak.

Wize what HP and tq do you think it will make?

I was hopeing for around 500 of each. I figured it was a big improvement over the 400 hp 318s in all the mag articles, little more cam(via rockers), little more compression, almost 100 cubes bigger, much better heads... if that 375 is all it will make then what am I missing?

The first thing missing is camshaft,the one you want to run is too small.You won't get 500HP unless the engine makes power @6000RPM. Rocker ratio won't fix it. You need 20plus degrees increase in duration and I'd go tighter lsa at the same time. A killer set of heads will change how much duration you'll need to make the HP you want. EDIT: I went back to a program that works on everything from Pinto's to Prostocks and although I still don't have enough info I plugged in a moderate Eddy head and the numbers changed for the much better than my first guess. 490ish ftlbs@3700,450ishHp @5200rpm. I still see it far from the 500hp mark but enough to run easy 11's with highway gears in an Abody.

The way you have it....honestly about 440HP with enough 2500 torque to pull a freight train....nice if that's what you want but as Goldmember is pointing to, you're gonna run out of pump (ve will be too high too soon and won't carry any RPM for HP in the upper range). Plus I think you're almost gonna need a NASA computer to control your timing curve to keep it from pinging on hot days at part throttle.

Long strokes can handle duration but IMO they NEED duration....look at the 455 Olds and pontiac factory cams, 300= running duration and they had plenty of vacuum for Power brakes and A/C.

You're kind of building the Mopar equivalent of a 428 Country Squire engine....lotsa low end thunder Thunder but no Lightning above ~4500...

For a flat tappet the minimum cam I'd run is something like 239/239 @.050, like the Ultradyne with the fast ramp intake and slow ramp exhaust, I'd cut it on 108 and put it in at 104....you'll have PLENTY of TORQUE and it'll chop at idle but you wont get any "camminess", even with a tight stall and gear. the tight centers are going to put the motor in happy zone quick like 2600 with your torque peak probably around 4000 and it'll still pull past 5500. That's based on all the parameters you have and this one will work best with the RPM intake...with 3.5's I'd run the M1 single.