motor locked/now free

[Ponderosa]

This is a 1986 40HO yamaha model is 40ETLK.
I picked up this boat from son in ga and it started and run for about 5 min. shut off would not restart.
Came home with it and motor was sized up.
I removed plugs, used some wd40 and sometime later was able to unlock the motor with wrench by turning clock wise and counter c/w.
I then thought i should check the cyl since compression was low 85 to 105. water passage bottom cyl real bad. look at all cly seen worse a little scaring and it appears one cyl is dragging when turn by hand.
Q How is the best way to free up then engine with doing a complete tear down and o haul.

[200090tlry]

I would try some PB blaster in cyl

Or some fogging oil spray some in carbs with throttle wide open. Then shoot some in cyls. I had 2 stroke snow blower locked up, purchased at garage sale. I let pb sit few day's and it freed motor up. Runs great today. Does the motor have premix 50 to 1 oil in gas. If your not sure I would not run motor again.