The guys that do my work have a 429 Ford in the shop now with the same problem, a sleeve took care of it.
The thing is if you have one hole thin with rust the others are probably in the same condition or not far behind.
Ive seen this too. The back sides of the cylinders look like moonscapes on a lot of these engines from that era. Some are okay though. A sonic check might not hit or pick up the crater spot that might create the pin hole.
Most likely, all the cylinders may be in the same rusty/moonscape conditions on the Backside, or it could only be just that cylinder is really bad, or had a really bad spot.
But that one pinhole, would be a( cross the finger moment), that it would/could be the only bad spot lurking on all of the cylinders.