Maybe this is a dumb question but I need to know if you automatically have to replace the pistons when you do a rebuild??

If you have to bore the block oversized, then yes you do. If you measure the bores and they are within limits, you can hone the cylinders, and put on new rings.:skull:

Man I have seen rebuilkd kits for the 350 go for as little as as $250. Just replace them.

Charlo