You don't need a crank, just a new rod.The crank is much harder than the aluminum rod, so all you need to do is remove the crank from the block and put it between a couple of boards in your vice positioned in a manner that the crank throw is open to work on.Get a strip of emery cloth that comes on a roll that is about a inch wide in fine grit, about a foot in lenght.Spray the crank throw with any light lubricating oil and work the emery cloth around the throw until the adheared aluminum is removed and the throw is shiny.Use mechanics hand soap to clean the throw and reassemble the engine with a new rod.I have fixed alot of engines with this method when I ran a small engine shop and never had one come back.