My car is very similar to yours in size and set up. I actually think you might be closer then you think. I would keep the carb you have, I had a buddy help me set up my 770 Holley street avenger and its jetted up some, but sticks rock solid for as long as I've put it on. I had to step up one jet size to make it perfect.

It sounds like a 750 double pumper is plenty of carb for your build. Streetwize sells a online book here, that talks a lot about street car performance.

Streetwize, in his book even claims that lots of guys with 440's get great performance using even a smaller 650 Holley DP, depending on the other factors in the build. Yet, for a build like yours, you would be hardpressed to need anything above a 750 dp.

Here is my suggestion from both the dyno and butt dyno. I run a Comp XE268, that I had degreed.

It runs strong and gives a deceptive, but nice idle with good vaccum for my power brakes. It also has a very workable power band

Mike