I think I would take the easy way out. Every few weeks a 400 bandit motor pops up on ebay and usually sells for no more than a couple of hundred bucks. You will spend more than that in gaskets just getting to the failed part. Granted, there is a risk in taking this route, but at worst you may be able to make 1 good motor out of 2 bad ones.
If your engine failed due to overheating or oil starvation, chances are there will be more than just one problem inside and it will be expensive to fix with new parts.
Good Luck.