1969 C10 Won’t start

[dtkarst]

I’ve got a 69 c10 that I’ve had about a year now. 350/350 combo, had the carb rebuilt, put an Hei in it etc etc. I fired it up today to get the timing adjusted just right (was just a tick off after hei replacement) and it fired up, I drove it around the block and it ran pretty great and as I pulled back into the shop it died on me. Went to start it again and nothing at all. I could smell something hot and got out and looked at the battery and the ground cable was loose on the battery and it was arcing a lot and the cable was warm. I snugged it down a little more but all I’d did was spark worse. Now I have nothing, no lights or anything just dead. Now my guess is I’m getting a short somewhere on a ground somewhere. They are new cables hooked up tot he right spots but the negative arcs all the time. Now the neutral safety switch was acting up ever since I bought it, as in i had to hold the shift lever up into park to get it to turn over sometimes. So what I’m wondering is, could my issue be in the safety switch or ignition, or somewhere else?