Was able to get some more days in working on the old girl. Wish I could devote more time and just get it done but I am making progress. Got the hood cleaned up, painted and the access doors working correctly.
Two weekends ago I reconnected the batteries and when the key was turned to ON the low oil pressure alarm was sounding and the garages were acting odd. It cranked, albeit slow, but started and I let her run for 10 mins or so. I had a huge voltage drop on the battery to chassis ground. Not surprised as the stud was corroded from being disconnected for over a year. I manually sanded it the best I could but it wasn't enough.
This past weekend I cleaned and secured the main ground. That voltage drop was eliminated but now when I turned the key nothing happened. The fuse box is 3 sections, 2 of the fuses had power, 2 had power when the lights switches were turned on but the row of 10 that powers everything else did not have power. I ran out of time to really dig into diagnosing the issue.
I will look at the wiring diagram and make a list of stuff to check. Since all 10 fuses are powered from 1 wire I would assume a relay is what powers up the box. So most likely suspect is another ground which is under the floor. I bet that is my issue. Everything worked before I disassembled to do the repairs.