There is a guy over on the Cast Boolit site that will help you design it the way you want. And will even draw it up for you. Then all you need to do is send the drawing to any builder. He has even done some group buys with Lee molds, for a pretty good price. However I am not real fond of Lee molds.

There is another guy over there. Off the top of my head I think he is called "Ranch Dog". I have not dealt with him. But all I have heard is praise for him. Tom.