The TBI ECM has a circuit that connects to the starter soleniod to tell the ECM that the vehicle is being started. Once the engine is running, the distributor provides an RPM signal to the ECM. his TBI motor already has HEI, the advance is controlled by the ECM.
What he needs to do is find a good wiring diagram for the donor vehicle - not this haynes/chilton stuff. After that, he needs to start from the ECM connectors and work his way out from there. Like you said there is not a lot of splicing, and he will re-use the current starter, coil power and alternator circuits.
The ECM needs a battery and ignition signal, the one wire that goes to the starter soleniod and a ground. The injectors each need an ignition circuit, as does the ALDL plug/check engine light. Once he has that, he just needs to plug everything in and go.