small block water pump bolt length?

Hi, Can some one tell me the correct length water pump bolts, the two on the bottom, I bought a timing cover and water pump bolt set from mancini and the two bottom water pump bolts are to short, they are 2", one of them will thread in about a 1/4", and the other not at all, I just want to make sure that when I get longer bolts that they do not go to far in to the opening of the timing cover. Thanks, Jeff.