I have an edelbrock intake which has a 70mm opening. Therefore I am planning on getting a 70mm throttle body. My question is this, would there be any reason to get a throttle body larger than 70mm?
It seems like anything larger than the opening to the intake would be overkill...
Nope...and with your setup it would give you anything but less throttle modulation anyways. A 70mm TB will support block splitting horsepower with your setup without being a restriction.