Im about to start rebuilding my engine. 2.4 so ive read up on em alot. If you can see the wall i assume u have the head off? If youre redoing the top end (which is what u should do if the head is off) then itll blow the bottom end. Redo it all. If ur unsure of the wall have a machine shop check it to see if it can be bored and magnaflux it to check for cracks then step back and punt. I may have $500 in good quality parts for my rebuild. And thats all gaskets bearings seals and rings, timing belts, tensioner/pulleys, water pump etc. I can expect another 250 in machine work and cleaning. So if you spend 1000 on redoing an engine on a free truck ur doing good.