Crank key extension

You cannot extend a crankshaft if that is your question. If you have an engine with a "stubby" crank, All you can do is get a different one.
Ground and polished and ballanced already.Cost $40 + $15 to ship and not always guarenteed the connecting area is good. Would rather spend that money on a cam if i could.
You can pick up the correct crank for under $40. Trying to make a stubby crank work is just pointless.