Rebuild to what standard and what engine? It really all depends on what is wrong with it. Is it just tired and low on compression? Is the oil pressure low? Bearings knocking? You can just do a ring and bearing job with a new timing chain in some cases, or if the bores are really worn you will also need new pistons. If the crank journals are scored, you will need to cut the crank. Spun a bearing? You need to fix a journal and align bore the block, etc. If it is a performance rebuild it depends on the intended application and how much power you want. Go get this month's Car Craft. They have articles on rebuilding a Ford 302, a Chevy 383 stroker and a Mopar 440 that will show you the basics. The Ford is a basic rebuild of a shot engine, so start there. The other 2 are performance builds and are not as useful.