Personally, with the heads you have, or W5 heads like I ran, I think the 4 inch crank is plenty, and well suited to both making power, torque, and longetivity, and reliability.
Bigger the bore the better. I also like the longer rod, ran a 6.300 rod.
At 4.100 bore the CP domes were only a hair over 400 grams.
Bumping your compression up like you are talking about with a 4 inch stroke and correct matching components will make more than plenty of torque to make your car 60 foot plenty good.
I know it can be done. I would strongly suggest a better block than you are using so you can reliably run a bigger bore, sticking with your current stroke,and calling Dwayne Porter and having him spec you out the proper roller cam once you get a good shortblock put together.
Edited by B3422W5 (12/07/13 05:56 PM)
69 Dart GTS, performance upgrades in progress