Valve cover engine ID
This is one of the easiest ways to figure out what engine family you're looking at.
5 bolts - FE big block. 352, 360, 390, 406, 410, 427, 428 in addition to the medium duty truck engines
6 bolts - Windsor small block. 221, 255, 260, 289, 302, 351W
7 bolts - Big Block. 429, 460
8 bolts - Cleveland. 351C, 351M, 400
Now that you've determined the engine family, there are other clues to determine which engine in that family you have.