Pic 3 That thick black wire with the yellow stripe need to be removed and provided clean connections to be an effective chassis ground.
Do you have any local "car people" friends that can come over and help you out, hopefully they have at least a VOM and a test light. Sorting out old wiring issues can be very frustrating - prior "fixes" often don't follow the color code.
Do one wire at a time from start to finish.
Back in the 90's I had my 72's wiring diagram from the chilton book blown up to A size, on the the back I wrote the tuning and torque specs - should have added part numbers too - then had it laminated.