It won't matter much, especially if you are just using it for parts and wiring. All the 2 barrel units are rated at 670CFM, and used the 454 throttle body with a square bore adapter on the bottom. They all use 85lb/hr injectors and theoretically should support 275HP. More fuel pressure would up that some. The 2D was the second generation computer, and digital. Any of the Pro-jection 4 units have 4 injectors and higher CFM, and would require the use of either resistors or the peak & hold board I mentioned earlier. None of the MS can drive 4 of those low impedance injectors without mods. They can support substantially more HP with double the fuel delivery capabilities. 90-93 Chevy 454 trucks are also good candidates for parts removal.