When I am in doubt about an old engine, I pull the head and fill the water jacket with Diesel and let it sit for a few days. If there is a crack, the Diesel will find it. Same goes for the head. Turn it upside down and fill the water jacket with Diesel. If there is a crack in the combustion chamber, Diesel will find it. Thats how we did it 65 years ago when these vehicles were worked and driven hard. I was 14 when I built an engine to put in a 1950 GMC to drive to school. I had no formal training, but I had watched some old mechanics. I still own a dozen trucks and supervise maintenance. But I still play with GMC and Y-Blocks. They were simple machines can be fixed with simple fixes. And before you bore an engine, make sure you can find pistons. They are very difficult to find.
