E.R. Shaw would be my first choice. They can fit and chamber a barrel in the length and contour of your choice, true up the action and refinish the barreled action at a better price than anybody I know of. I have a .270 Rem. M700 and a .358 Ruger M77 that were done by Shaw and they are tackdrivers.
You can build the rifle online at their website. Just Google ER Shaw gun barrels.