Well, that's what I'd have to term a 'butchered bitsa', especially with the weird mods to the muffler.
It's basically a 1950's engine and blade disc, on a 1970's Utility chassis.
If the engine still turns over, it
may be salvageable - water in the cylinder is not necessarily a major problem; water in the crankcase usually is, due to the rolling element bearings in there. Best thing to do, is to strip the engine down pronto, and give the big end and main bearings a good shot of something like WD-40. I'm not an admirer of WD-40 as a lubricant, but it does do a good job of displacing water.
The teardown will be a good exercise in getting to know these engines, anyway.
You'll need Whitworth [BSW/BSF] spanners for the barrel, head and crankcase nuts though, and either a 13/16" or 1" AF ring spanner [or that size socket and an air rattle gun] for the blade disc nut.
There's a bit of a trick to getting the crankshaft boss under the blade disc off - see
THIS past thread.
