I just don't get why you want someone else to develop the load. Developing loads is the all the fun in this sport. That is why I have 55 rifles of currently uncounted calibers. There is no doubt that the process of load development can make you tear your hair out at times, but that is the case with any sport. But having a custom rifle
built and then paying someone to develop a load for you when you intend to start loading yourself is like buying a new set of golf clubs and paying someone else to play with them. Buy the rifle, whichever caliber, and have the satisfaction that you have done the homework and the hands-on work to come up with a load. Yeah, the first few loads may measure a couple of inches, but then all of a sudden you hit it just right and shoot a half inch or less group. That is incredibly satisfying and the reason I have so many rifles and calibers including several wildcats. Once I solve the puzzle for a caliber then I have to try something new. Frankly, if I buy a new rifle, take it to the range, and the first box of shells all group about half an inch, I am disappointed. There is no challenge. Don't buy a nice rifle and then let some other guy have all the fun with it.