I have 2 440 blocks, one '66 & one '77, both are in cars & .030 over with about .220 minimum cylinder wall thickness left. Both had a fair amount of core shift, otherwise they'd have about .260 left IIRC.
Sonic testing is something I consider mandatory for any performance build before money is spent on pistons & machining. Also, for building HP, I prefer thicker walls over getting the next .010, .030, or whatever bigger bore.