302 or 351?
The two easieast ways to check is to look at the thermostat housing. If the lower bolt is behind the water pump then its a small block. If you can reach the lower housing bolt with out going behind the water pump, its a 351. Another thing to look at is the timing cover. If the top of the block is flush with the top of the water ports going through the timing cover, its a small block. If the deck of the block is about 1 1/2 inches above the timing cover, its a 351.