Either manifold will work as they are both dual plane though Edelbrock claims a higher RPM band for the RPM version.

A 750cfm carb is WAY, WAY too big for a street driven car that sees little high rpm operation. The OEM 460 Ford ran a 500-525 cfm and got reasonable(??) gas mileage for the time. I tried a 780 Holley 3310-1 on my long gone '79 460 truck - gas mileage went from poor to abysmal and with the performance also going away.

Here's the industry accepted formula for determining carb cfm:

CID x RPM x V.E. / 3456 = CFM

428 x 3000 x .85 / 3456 = 315cfm

428 x 4000x.85 / 3456 = 421cfm

428 x 5000 x .85 / 3456 = 526cfm

428 x 6000 x .85 / 3456 = 631 cfm

Looks like I'd be considering a 600 to 650 max carb Which means at any of these RPM figures, you don't need that much carb. And with gas at $3.75/gallon,,,,\\\\\////???