I would suggest you check with some local transmission shops to see if they know of anyone close.
I go to TCS in Langley B. C., Canada for converters for my car. If you want to talk to them, talk to Jim Jr. at 604-533-8675. They are about 30 minutes the other side of the border. They are a large shop, about the size of a medium size warehouse. They build race converters and can do almost anything you want.
HTH