ok its always a little tuff to give what size carb to get. but here goes. do you have a heavy foot??? or just cruize, mild motor or is it goona get going???  i would prob start with a holley 750 db hell maybe 850. try this holley has a web site that will go thur what you want and need . and in the end spit out the size carb they think you should get. Good luck.

I have a demon 750 dp that needs A rebuild kit, just gaskets and one accelerator arm. Pm for details

A 750 demon flows really good. Unless your drag racing a single 750 will do fine for awhile. You know NASCAR used to run a Holley 390 and 355ci before the file injection. Jut saying don't over carb.

What about the difference between the speed and the mighty versions? Should I get the mighty with no chock tower since I won't be using one anyways? Or is this to much carb for a mild 402 ( I will be changing back to a 454 at mid summer 402 is my back up motor)

I agree with crewchief .