Many competent gunsmiths could chamber a barrel into a prefit off of the print that you have shown. There are probably dozens or more members on this site that engage in this type of work daily. I won’t post any names because I don’t know who all are contributing commercial members but the process is rather simple with today’s equipment compared to 25-30 years ago when you really wanted to be selective on who did your work. Depending on where you live there is probably a good smith within an hour of you that could thread and chamber off your specs as well. Thanks.