For a pure street engine, you won't be spending much time at higher RPM's so don't worry about the flow numbers falling off. You're going to benefit from lighter heads and new intake components. The rear gearing is entirely your choice, but remember, the big block 440 does not need a ton of RPMs to make power! My preference is the 3.23, which is a good all around gearing for highway & city. You have a pretty light car too which means you would not necessarily need 3.55 or more gearing to get moving quickly. The other consideration is your transmission. A higher than stock converter will help you get moving without the lower gears killing your fuel economy.