Compression ratio really depends on the entire combination. My old 451 ran on pump gas at 11:1 compression, with a mild 251/251 duration roller cam and Brodix B1 B/S heads, 3500 stall converter and 3.91:1 gears. The new 500 stroker is 12.4:1 compression, and I have been running it on 100 octane pump unleaded. I have not tried it on lower octane. I really built this engine with the intent to run E-85, but I need to update my fuel system for the E-85.
I also, have a 440 source 512 kit that I plan to put into my convertible. I want this to be a pump gas engine that is easy on parts, idles like stock, and good power up to 5,500 - 6,000 max.
I am using the 440 source 17cc dished pistons #5070, and with the Stealth heads 80-84 cc? the compression ratio will be about 10.0-10.25:1 depending on the actual chamber volume.

With 512cid the Stealth and RPM heads are actually on the small side and could use some porting, but should work fine on a street car.

The big engine will really want a good sized cam. I think about the smallest cam I would use would be 230 duration @ 0.050".

I have not decided on a cam for my engine yet, but I have the old 251@ 0.050" roller cam from the 451 I was thinking of using as a baseline, but I really would rather have a milider hydraulic roller than the solid roller to reduce valve train noise. Because i don't plan to race the car, I am leaning towards a smaller cam, and looking at something like the Comp #3122 hydraaulic roller cam lobe profile with only 236 @ 0.050" duration, 0.608" lift with 1.6:1 rocker arms, but the ramps must be pretty fast because the 0.200" duration is 160 degrees which is about the same as some of the larger 244(158&161) and 248(161) @ 0.050" cams?

My Suggestion is to look up AndyF 's Mopar Book.. ASAP

AndyF's BOOK

11:1 will work well with the 557 and it will make great power even with mildly ported E-heads. Think about a 2.19 intake valve and concentrate primarily on getting the mid lift numbers up, don't worry so much about the peak numbers.

I like the Indy dual plane (I run a ported Max wedge version on my 4.30 stoke 12:1 517 B) or the street dominator, the performer RPM is also a great intake but it is tall and limits your hood clearance and doesn't flow as well as the Indy 2D on a big inch motor.

Your short block makes the torque, the cam tunes the curve and the HP potential is the heads....get the powerband where you want it and if you want more HP upgrade later to some 360+ cfm MW ports and you'll make more big end and not lose any torque, only gains.

557 is a great cam, it will be very mild in a 511, at least the way I build them. 590 would work even better with no real downside on the street.

For street strokers I like a tighter (3500-ish) FB stall with a ~4400 flash...but your in a "race only" forum so the opinions are going to skew to the high side. The tight FB allows you to get more use out of the great torque but the flash puts you right into early side of the flat Torque Peak so even from gradual part throttle 'roll-on' the power comes on fast with great tractibility on street tires....plus it's more predicable and easier to modulate in all weather conditions.

PM me if I can help with any 'real street' combo type questions.

None of these 10.5 to 11.5 combos would run very well on the 91 pump gas that they sell around these parts and that is the best you can do here unless you go to E-85 and then you would have to travel 200 miles to get that.....so pump gas friendly is very relative to where you live at.