After this much time and that much trying to crank it over putting a lot of stress on the lower end parts trying to compress water....I would say replacement motor.
Trying to crank it as much as you did with the water in there not able to be compressed is quite back for the wrist pins and bearings. Also..ithere was water and coolant sitting in at least one cylinder with open valves. The chance of rust in that cylinder is pretty high and that rust could have destroyed the rings when you cranked it over after all this time.
00 Regal GS: All kinds of cool stuff.