The M112's haven't had a big cylinder head history, and as far as I know have no problems with the bolts either. The cylinders can't be bored out, however, so ithe crankcase is a junker if the walls are scored.

Good condition used parts should have value, but you'd have to check the auction sites or call some place like Potomac to get a feel for how much. Since these are still common engines, maybe lower than you hoped.

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