My 70 Malibu build

[Quadracer392]

Got the car running a whole lot better this evening. Used a different carb from a buddy of mine. I've rebuilt mine twice and it still hasn't fixed it, so it looks like I'm going to get another one. What's some suggestions for a good carb for a fairly mild street motor? I've always run edelbrock and it's what I'm used to but open to others like Demon, Holley, Proform, another edelbrock? Thinking I could get by with a 650 or would a 750 be better?

Here's a quick video of it running with just the headers.
http://youtu.be/yDaE0V--Dfw