are still available, probably the easiest and least expensive solution is rebuilding or partially rebuilding the 5411. The good thing is that the liners are bore-able to .020 oversize or can be replaced.
manual is found here:
To get the engine
unsiezed, take off the head
(loosen the bolts incrementally in the reverse order shown on page 12 of the above manual.)
Take off the oil
Take off the connecting rod cap bolts and caps. Do not mix them up. keep them with their respective rod. Take a long, preferably hardwood dowel, and insert it as best you can into the underside of the piston and drive the piston out through the top of the block with a medium heavy steel
hammer. Do the same with the other piston.
You'll probably find that this frees up the engine
, the bottom end of these engines is exceptionally robust. If there was no water
in the crankcase and the crank spins freely, it's probably ok. The condition of the rod bearings can tell you a lot.
I did a poor mans' rebuild
(rod brgs. rings, honed the cylinders, unstuck and cleaned the injection pump, replaced governor bearings) on a severely flooded M20 about 12 years ago, at the time I lost
track of it about 4 years ago it was still running strong.
Your intended use of the boat could
reflect the amount of expense you invest in the engine.....