I recently done the same thing but I had no issue with the starter. I used the starter that came with the engine. I have had to shim starters on engines, especially chevys. They sell them at most parts stores. When you say no starter will fit, did you mean the bolts will not line up? It should take two 3/8s bolts about five to six inches long and should go straight up into the block. If this is not the case, the donor engine may not be original. If it's not engaging the flywheel at all, you may have the wrong flywheel. If it's hitting it, shim it. Answer back if this doesn't help.