You will have to open up the rails of the action a bit to get the rifle too feed. Also a bit of grinding on the feed ramp will be needed. One of my customers had his .375 rebarreled to .470 Capstick by MRC and when he got it back it would not feed at all and that is what I had to do to get things right. I also glass bedded the rifle and it had no barrel lug but with the double cross bolts and bedding it has held up fine.
I have also heard very good things about the work done by Clearwater Reboring, I think that is who Doug Turnbell uses.