Good pic with a bad caption. That's a Ford 2.3L cylinder head, not an engine block. If you have any aircraft repair facilities or oil fields in your area there is probably a Non-Destructive Testing business somewhere that can do Magnaflux, X-Ray, Zyglo (non-ferrous metals), and others that I've probably never heard of. Testing as suggested sounds like a very good idea to me. Or keep the actual action itself and replace the barrel and the bolt. I'd still test the action if you do that.
I think that I'd let it soak a while in some bore cleaner before I tried anything further. Put it lugs down submerged in a small tray and cover the tray so the bore cleaner doesn't evaporate too fast.