Im sorry already... electrical issue

[Yupiamlo]

Hey I have a 1985 Chevy C10, 2wd 305 TH350. We did a motor swap to it this past weekend and its running and driving great but...

Today when I went to start my truck I turned the key and nothing happend, the buzzer didn't buzz, and the head unit had no power, my lights worked though... I popped the hood jigged wires, got back in and it was all good.

Later it did the same thing to me at wawa, but I opened the door and I guess it jiggled enough to be ok and it was good again.

SO my question is what wire would do this? The only thing I can think of is maybe one of the wires down to the starter is loose? Cause I know they can screw you sometimes... Ne ideas?

Thanks in advance