I am not an engine builder, but here is what I suspect.
If it got hot and 2-3 pistons are clean, it got really hot. Head is probably warped beyond use. You may be able to make the gasket surface flat, but the cam journals are also warped. Causes drag on cams which cost HP. Rings are probably also junk. Oil may not look contaminated, as most of the water burnt off, but the water gets into the bearings. Water is not a good lubricant. Expect the bearings to be damage.
Short answer, start over
Sorry, Dave
Dave Wheeler
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