There are multiple vendors selling repair kits for stripped out threads. Helicoil is the name it took me a minute to bring to mind. That is, I think, the original thread repair product, dating back to aircraft engines made of aluminum where a lot of machining would have to be done to replicate a part with stripped threads.
Do a search for 'stripped thread' or damaged thread repair or pick your own phrase.
Essentially, you find the product that will allow use of an original sized bolt, and the 'kit' will come with a drill bit that can be used to size the original hole for threading. The next step is to cut threads for the insert, then install the insert and 'lock' it in place using the proprietary mechanism(expansion, barbs, I dunno). Finally you end up with NEW threads, that are threaded into an oversized bore that has had threads cut into it. The new threads are the same as original. These kits are used regularly in the FoMoCo 4.6/5.4? that have the loooooonnnnnnggggg reach spark plugs. Said plugs, from the factory, were a bit too cheap, and with extended change range, were solidified in place by the time someone tried to replace them. They come apart, and sometimes eat the threads.
Ford has a kit for them, FWIW.
The Lima, being cast iron, doesn't run into as much problem with stuck plugs. There was a recent post where the spark plug(drivers side #3) broke off the top of the 'base', leaving a ceramic center, and the outer of the plug - no hex left. He got is out using the OHC Ford tool, I think. That is the only Lima plug problem I have heard of, and I bet those plugs were still the factory drivers side.
tom