Locked Engine, what to do?

I'm working on my grandpa's 86 Honda VF700C magna, and the engine is locked. Starter won't turn it over, can't turn it with a wrench on the alternator bolt. Plugs were taken out, didn't help. Clutch is free, and it shifts through the gears. It's sat in a heated garage since it ran last (two or so years ago) with plugs in and carbs on. Not sure where to go short of dropping the engine and pulling the heads.. Any help or suggestions are appreciated!

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based on your info, your garage was not heated and/or dry enough . . the rings rusted to the cylinder so you need to rebuild the top end . . pour around 2 oz's of kroil oil in reach cylinder then let it sit for two days then pour 2 more oz's then let it sit 2 more days then try to turn it over . . if it doesn't turn over, you can remove the cylinder head and lightly whack the pistons with a 2 x 2 and a hammer.

Shit, alright. I was holding on to a faint hope that it could be something besides the rings rusting up. So if the kroil frees it up the motor is still coming out to get new rings and a hone (depending on the severity of rust and pitting)

In case anyone wanted an update... It was the drive gear for the oil pump binding. Bike is running now.

Awesome. I love a happy ending