Any of these guys can do the coversion for you. Alan Harton, John Gallagher, Jim Stroh, Andy Horvath, Hamilton Bowen, Ben Forkin and David Clements. All have done work for me and caliber conversions such as what you asked about or normal stuff for these guys and they all do great work. Andy probably has the shortest lead time right now. I know Alan, Jim, Ben and David are normally about a year or so last time I checked with them. I've had John do a old model 357 conversion to 41 Mag and Andy do an old model 357 to 41 Special and hamilton is currently doing an old model 357 flat top into a dual cylinder 41 Special/41 mag so you shouldn't have any problem with the job.