Faulty starter solenoid killing car?
Replaced the yellow wire. I guess we'll see if it's a long term fix. I am concerned now though. I can't seem to find any fusible links. I don't know if that's because the previous owner may have removed them during the engine swap or maybe I just don't know what I'm looking at. I'm not seeing any reference to fusible links in the wiring schematic I'm looking at and the service manual only refers to it once in regard to the voltage regulator.
Also, something else I've found out, since they converted this to an automatic transmission, it appears the starter relay should be grounded through the park, neutral lockout of the gear shifter (neutral safety switch). They currently have it grounded directly to the firewall. I haven't tried to start the car in gear to confirm, but this is what I expect the behavior would be.