Sleeve in new barrels on a double rifle..

Gents..

I have an extra set of barrels for my .475 double. They are in .280 Flanged NE. This is a pretty oddball round and not so easy to load for....too easy to get high pressures....and the rifle is then really much to heavy for calibre..

So I contemplate cutting those barrels and sleeve in a new set of barrels in either .375 Flanged or 9,3x74R and subsequently scope the new set with controlled claw mounts..

Have any of you done similar jobs..?