360 balanceing

Ok I've always heard that a 360 needs to be balanced even if ur just putting in new pistions and rings. So what do i need to do to get my 360 balanced. What exactly does the machine shop need to balance my assembly. Also how many of the member have actually did this and how many decided to skip the balanceing act even thou they're running new pistons. Also if it's not balanced does it matter if the rods are put back in to the same bore. Thing is, if this is necessary what do i need to run to the machine shop with, block, rods, pistons, crank, etc..... Thanks.