I didn't think I was going to be able to find a local who could weld the braces onto the lower housing for me...
Clint at Warragul Steel Sales is doing it for me now, he used to build race winches all the time so he is the man for the job.
He is also going to modify the drum end to take the bearing for me. I asked him about smaller drum diameters but he said if I'm not racing it's probably not worth it.