360 LA squeel / scraping noise like drive belt on passenger side

The dude that put the motor together may have put the rods on the pistons backwards. There is an inside edge and an outside edge, or to say it another way, one edge of the crank end of the rod is chamfered and the other edge is flat. The flat edges always face each other in the middle of the journal and the chamfered edges always face the counterweight. If you look at the outer edges of the rod journals on the crank, you can see why they have to be that way. Might not be what caused the problem, but it is a place to look. Sorry for your troubles. :(