Hi and thanks for entering your forum, I have a casting number that makes no sense at all!
EDB 6015
I have been trying to search on this number, and all I get back is that it is a Y block
It is not a Y block, have anybody got an idea about this number??

Looks like your intake is dated October 12, 1957. If that block matches it is an early 58 which was just before the "box car numbers" 575XXXX. I have heard of some 430 blocks going .120" over and stroked with Jahns pistons. My 1960 - 65 blocks have been good for .015 to .080" over. Maybe yours is one of those extra thick blocks?