I completed the tear down of a salvaged 1957 marine 272 with G heads.  I'm curious if the bulls eye pattern on the tappet surface indicates anything?   Almost all of the tappets had these faint circles, some more than others.  Maybe scratches on first start when new?  Unfortunately, the block's water jacket had cracks on both sides but the internals were all very clean.  The camshaft looks good and is 57 spec with the end stamped Z 201. The G heads found a good home and the rear sump oil pan went to a desperate T-Bird owner.