I hope the ECUs don't communicate over a CAN. If so you might have trouble with ABS, SRS and the convenience module if they expect to communicate with a particular ECU.

I don't look forward to the wiring harness simply because I don't enjoy that type of work

You might need a Diesel Klima or ice cube relay.

It'll be interesting to see if the gasser tach works. And cruise amp.

Can a gasser fuel inlet pipe be modified to take a Diesel nozzle?

Sixto
87 300D