Choosing A TB For A Magnum
The size of the TB has little to do with it. You are not trynna produce vacuum signal as with a carb
Biggest thing I think with NA EFI is "ram length" IE manifold design, runner length, etc.
The old Holley TBI on my 318 is 950 CFM 4 bbl!!!
Too small and it will act like a choke at WOT
"Really" large and my perception is that you get into a control problem, IE you move the throttle a tiny bit (slow street driving in traffic) and "that great big throttle" opens by a large percentage for a small input