Thank you for the info this helped a lotOn a 302 (or smaller c.i.d.) blocks, the distributor mount is almost flush with the top of the block (where the intake sits). The water passages are also right at the top of the block (where the heads sit).
A 351W block is taller. So, the distributor mount is below the block surface where the intake sits. There is also more space between the water passages and the cylinder heads.
This info was taken from summit racing: