If it cooked as badly as you reported, it may have "heat treated" the rings to the point they've become less effective, most other components will have been exposed to water and will possibly rust. Best to disassemble all and clean thoroughly. then lube all with fresh oil or grease until ready for reassembly.
That pulley nut is HUGE and should have a lock tab as a retainer. Bend that flat with the pulley first. The best way is to get a six-point socket at Sears to fit it (1ÂĽ" IIRC). A L O N G breaker bar would be good if you haven't a compressor and air wrench. And you will need to "pin" the crank to keep it from turning. A piece of 2x4 wedged between block and a crank journal does well.