When looking for Big Block throttle body they are all same bore size but three differant injector sizes.
5235231 - Red / Blue - 80pph - 7.4L / 454 - 88-90
17084304 - Black / Blue - 76pph - 7.4L / 454 - 91-93
17104288 - Pink / Purple - 46pph @13psi - 7.4L / 454 - 94-95
*NOTE: Came with 30 PSI regulator used @ 26-32psi for 67-72pph
About the only thing I know about aftermarket EFI control units is after a few years they are paperweights and can't be repaired or replaced?
There are factory GM ECM with boost, Syclone and Typhone 1227749 with mask ID $58. There is also an enhanced version Code 59 that will run on 1227730 GM ECM.
If your looking for something to tune yourself with boost there is an option for GM ECM that also has VE learn.