Studs Snapping
I'll leave the electrical problems up to others, as I don't pretend to know much about the subject, but I am eager to learn. As far as the snapping stud or mount problems go, the Theory is to Limit the sideways 'flop or twist' of the motor caused by the torque as you accelerate. On all of our cars that we used to drag race, even the ones we didn't race, we Always ran a chain or steel cable from a bolt on the front, left (port) side corner of the block directly to the left main member of the frame. It was taut, and as you mashed the gas, the block wanted to violently flop to the right (starboard), shearing the rear motor mounts. In 1968, GM even issued a recall of their vehicles with V-8 engines to correct this problem...the 'fix' was merely a steel cable to the left frame member.
Check AusieSteve's profile, 2nd & 3rd pics to check out his rear motor mount...a very good example of holding that motor tight so it can transfer all power to the rear wheel only. Ron's 'L-bracket' (Al.Fisherman) seems to do about the same thing. Anyway you can figure that if you keep that engine from lopping over it will eliminate the problem of sheared studs or mounts. I know it is hard and frustrating, and you get madder than heck at everything and everyone; but, I find it always helps to just sit on a low stool and stare at the thing. Pretty soon something will form in your mind, clear as a bell, and once you know the Theory behind what you are looking for, you will have a solution to what is causing the problem, and be able to fix it. Good Luck.