Sonic testing is the best way to proceed.
FYI, regarding racing applications, John or Geoff Mummert and Joe Crain, don't recommend boring a 312 block, more than .040. It's been said that the cylinder cores are the same on on the 292 & 312. I'm not a Y-block guy so, I have no experience with them, but, Geoff & Joe, have a lot of experience with them. There is one more that can be consulted, Ted Eaton:
https://www.eatonbalancing.com/2000/...cing-articles/
Any of those 4 people, can tell you what is what, on a Y-block, it's how they make there living.