So, it looks like this is actually happening. Schematic is probably 1/3rd done.

Looks like it will have:
Inputs:
VR speed sensor input (two wire)
12v PWM speed input (hall-effect sensor)
TPS
MAP
RPM?
4-LO
Overdrive disable button (any reason to have a lockup disable button?)
Stuff from the transmission


Outputs:
12v PWM speed output (to drive speedometer?)
status LEDs
header to transmission (obviously)

Other:
USB (will have a software program to set up parameters)


Is there anything I'm missing? Anything that would be nice to have?

I will also need a guinea pig someone with a running RE transmission to help me test everything.