Here’s a few possibilities:

https://leverguns.com/leverguns/leversmiths.htm

I think you might find the following thread of interest.

https://castboolits.gunloads.com/sh...nfo-for-browning-71-to-50-100-450-wanted

I’d be inclined to talk to John Taylor, mentioned in the above thread, and see if he would take on the project.