Thanks to all for their thoughts on this problem.
On Monday I contacted a friend of mine. A retired Delta Airlines mechanic, I had met him because he had an Allis-Chalmers Model G like I have. Mostly we had laughed & scratched at an annual local Farm Heritage Days event so I knew of his welding skills mostly by reputation. I had used him one time to do some aluminum welding on my trailer and I was impressed by his work on that project.
On the phone I told him I had a broken gear that I believed was cast iron. I asked if would look at it and give me his opinion on if it was a repairable situation. He said to bring it to his shop and he would look at it.
I drove about half an hour to his place and he examined the gear. He stated he thought it was repairable. I asked him if he knew someone that could do the repair. He replied, "Yes".
I asked, "Is he close?" He smiled a big smile and said, "Yes".
He gave me a quote on the repair and I left with the gear. I still needed to negotiate with the eBay seller on a reduction in the price to offset the cost of the repair and other incidentals.
By Tuesday morning the seller and I had come to an agreement that allowed me to keep the gear set with some compensation for the damage during shipping. I called my friend and asked when I could drop the gear off for repair.
He told me to bring it right over and - because he was busy with other projects - to leave it in a designated location. I did this at about 11:00 am yesterday. I had already told him there was no hurry in getting this gear back to me.
This morning I got up and, as I was drinking my coffee, I was thinking about calling him to see if he had found the gear. As I was considering when would be an appropriate time to do that, my phone rang. It was my friend: "Your gear's ready.", he said.
He indicated he had welded it with silicon bronze. I'm very pleased with the repair.
Scott