Jerry as has already been mentioned, most people tend to overcarb their engines, particularly street engines. For what I presume you're planning to do with your car the best thing you can do is go on the small side for a carb. You'll find it to be more responsive, particularly at low rpm's where you're likely to be spending most of your time. The reality is 6500-7000 rpm runs won't be happening so much for you that you'll miss the extra capacity.

I've been through this myself many times over the years, and in each case have found myself happiest with a street car running a 600-650 cfm vacuum secondary carb. I'm partial to Holley's myself. I've struggled with a few Edelbrock's and AFB's. I think the Holley's are easier to understand, particularly for an idiot like me.

Realize you're not talking that much money that you can't upgrade later on when you re-do the engine. There's always a good market for used Holley's. Once you've done the top end work, sell yours and go for a 750.