Kraig,
The crankshaft on my 129 looked like yours last year. My pulley was also wore badly. I found a used pulley that was tight on the crankshaft, put a longer key in and ground the end like the one for your Killer Kohler, and used either JB weld or liquid steel to fill in around the key. I let the filler harden and filed it just enough to get the pulley on. It ran all last year to mow the grass and has not come loose yet.
The crankshaft on my 129 looked like yours last year. My pulley was also wore badly. I found a used pulley that was tight on the crankshaft, put a longer key in and ground the end like the one for your Killer Kohler, and used either JB weld or liquid steel to fill in around the key. I let the filler harden and filed it just enough to get the pulley on. It ran all last year to mow the grass and has not come loose yet.