If compression is low, yes a ring soak may and often does help. I'd try soaking the rings for days with occasional movement of the crankshaft. That engine has a rope rear main seal which could easily be damaged by solvents in the oil, I'd avoid cleaners added to the oil only soak them from the top.

I wasn't crazy about my HF tester.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer