Unsticking an unused engine........

Check post #48. Seeing that you now have the it on an engine stand, I suggest that you remove the rod bearing cap on cylinder #2. See if you can rotate the crank away from the piston rod. If you can, 2 is the problem. If possible, I’d remove all the piston you can then set it #2 cylinder side straight upwards, then fill the #2 cylinder with the 30% white vinegar. Cover it up and wait a couple days, then empty it out and try to “tap” it up or down with a wooden block and hammer. Repeat as needed. This method worked great for me.