Any one have a crank for a 1979-80 RM400 laying around ?

I have a 1980 RM400 I bought from a feller who was a lot slicker than I am. He said the bike had been a runner and locked up while it was stored. Piston was seized on both the exhaust and intake side ( badly ) but that I could deal with. It also sat with a case full of water and ruined the crank. Trans is fine and the rest is useable but the crank is done! Hope some one has an idea where I can find one