I'm going to add my two cents and try to keep it short.
That ridge you have to cut out is the size the bore used to be and is correct for NEW original pistons. When you try to get off the hook by just busting the glaze and re-using old pistons, you open the door to some potential problems.
Depending on skirt to wall clearance, the piston will rock back and forth in the bore at TDC and BDC. This can make for noisy start-ups that hopefully goes away when the engine warms up. The rings can also unseat with every rock of the piston. That increases blow-by and can also make for a new engine that uses oil. The ring gap will likely be several thou too wide, also adding to a blow-by problem. It won't build the cylinder pressure it should, either.
If your blow-by is enough to overwhelm your PCV, the crankcase will build pressure and you'll find that your new engine weeps oil in addition to using it.
I'm not trying to give you a "doom and gloom" post but I want you to be aware of what can happen. Personally, I'd bore any old, carbureted engine. You could probably get off the hook (safely) busting the glaze on a modern, fuel-injected engine with under 75k miles or so but there's just too much bore wear on an old anchor. I'd have it mic'd and bored to where ever it needs to be to fully clean up the bores and get new pistons and rings.
Do it right and you won't have to touch it again.
Edit: I see where you stated there was no ridge. I must have mixed this thread up with another one. My bad but these points should still be at least entertained