If you don't already have at least one flat braided copper grounding strap connecting the engine to the firewall, I would add one pronto. I don't know if you are running an automatic trans or not, but if you are and you don't have a ground strap to the firewall, the grounding current will flow through the trans selector cable to ground (assuming that you have console shift). I know it sounds crazy, but I've replaced shifter cables on several Camaros and Monte Carlos because of that very problem. The shifter at first gets a little stiff and then all of a sudden you can't move it at all; it usually sticks in D and you don't find out until you get where you're going and can't move the stick when you stop. Like I've said, I wouldn't believe it was possible unless I had seen for myself the corroded shifter cables that came out of the cars. In every instance, the ground strap was either missing, unscrewed, or not making good contact with the firewall. If you do put a ground strap on your car, be sure to put an external tooth star washer under it so it will bite into the sheetmetal of the firewall when you tighten it down. As for your sparking bolts, I've never heard of that before, but I agree that you should remove the negative lead to the battery so you can't complete a circuit to ground.

Randy