[supra_ma61]

:?: I want to fit DCOE carbs to a manifold, but do I use 40's or 45's to feed the thing with :?:

 

[Tommy]

40s will be easier to tune and give you the best throttle response. 45s will be harder to tune in the low-midrange but give you the most max output. Plan on a fuel line upgrade and a high volume/low pessure pump to go with them.
Keeping them in sync will be equal.
Good luck!
Jamie