You could send them over to the UK and have Bill Blacker do them.
He is the best. Check out his web site.
I have a friend who has a Purdey Pigeon gun that once belonged to the King of Spain. The barrels were so tight he had them sent over to Bill Blacker to open the chokes and have them re-proofed.
There are people here in the US that could handle getting them over there.
He makes barrels for many London Bests.

Mike Proctor