Don't forget that most of those cars have multiple computers and systems, most of which can put the car down if something isn't right without even being related to the drivetrain. If you narrowed it down to only those with PCM issues, I bet it would be pretty small. Not saying it isn't possible, just that it might not be as bad as you think.
Hardly anyone is doing a full wiring harness swap into an old car anymore. I'm going to run mine on an OEM PCM and might add the ABS module to get a vehicle speed reading but beyond that I don't need the BCM, radio, bluetooth module, TCM, ect.
To be clear, I do plan to build up an Arduino to put the CC messages on the bus so I can run my old school column switches and still have the PCM control the vehicle speed like it would in an LX/LC. So that is another module, and certainly an additional failure point. Nice thing is, if it does fail, it doesn't brick the car.
