American Motors: water in oil, cam bearings, rod bearings

Question
Hello, got a engine that was just rebuilt, left the valve covers off to adjust valves, rained and water got in oil, alot of water, (not my fault someone else) changed oil but now sounds like could have main knock, could water have damaged bearings? and would just changing crank bearings fix it or is a complete rebuild in order, cam bearings, rod pins, ect.?

Answer
How long was the water in the crankcase? Could be rust on the inside got into the bearings and wiped them out after you had the engine running. Mains, rods, camshaft, lifters, cam bearings.
Was the engine cranked or run with the water inside? Probably damaged the bearings and possibly the cam & lifters.
The best thing to do is inspect the main bearings and crank journals; if either are scored, replace them and the rod bearings. Pull a couple of lifters and see it they're scored.
It would be nice to find a boroscope to inspect the cylinder walls, too.