I have owned several over the years ,and most of the more knowledgeable Flathead guys in my area have passed away or moved on.
Ronnie Roadster is one of the best I know in Connecticut. He is on the HAMB (ronnieroadster) Al Clark ( Go Devil Garage)in Schodack NY is supposed to be good. I have never used him for a motor but he has done some rear end work for me. Not sure if he is on the HAMB. Ronnie has completely rebuilt a motor for me and I could not have been more pleased.