Hello John, a big WELCOME ABOARD to you and your dad, and congratulations for scoring one of the iconic 38s. It's a comfortable and fast hull I think you'll enjoy.
On the wiring, be sure to use tinned marine wire and not the hardware store or automotive stuff. The non marine wire will corrode inside the plastic insulation. We've owned our 38 for 13 years or more, and I've never seen a wiring diagram yet. As you can see here in this thread, Curt Hill has a wiring diagram for a 38 SF, and its probably similar to yours and my 38, but the SF has more in common with your sedan than my express.
Rebuilding the 454 sounds like an interesting task, do they have the cast in "wipers" on the crankshaft like the big block Ford FE, and the directional seals? Just curious if GM had a "better idea".
If I can get my hands on a wiring diagram I'll surely send it your way. In the meantime, hope you feel welcome and comfortable researching your project, and ejoying the technology offered here by the members of The Forum.