Formula to shave pistons to reduce compression ??

Rdrd to determine how deep it is
I wasn’t able to negotiate the price down , enough plus the guy has other guys willing to , take it as is without sonic testing. Plus there is a gouge in the wall and it’s hard to determine how deep it is , Too many unknowns, ifs, then, but, maybe etc

Find a good block and built it right, the way you need. Someone else's damaged goods is just that.