I did a homemade flow test of the Vortec 454 injectors using a stop watch and a large cc syringe, and came up with about 19 lbs at 45 psi (3 samples on each of the 8 injectors). The '7730 ECM I used...

Probably is the same throttle body. I posted the pics to show how the factory kept the intake runners long, with a low profile. The pics also show how the factory was able to increase plenum using...

Maybe the option of a late 90's Vortec 454 Throttle Body? U-Haul used the same throttle body on the Vortec 8.1 liter truck engines. The pics are from a 99 454 Vortec.

dave w