Dan, the only damascus barrels I have heard the English making was Greener from tubes forged up a century ago. Peter Dyson also has some of this old stock too. And they are being made into shotguns which are capable of being proofed to CIP smokeless pressures for shotguns. The English are also routinely reproof damascus barrels guns made in the late 1800s for smokeless pressures in shotguns. Proof pressures would probably not exceed approx 18,000 psi for service loads around 11,000 psi.
The damascus steel being made from the powdered metal process is mostly stainless steel and might not fit the bill for a high art custom longrifle. Not sure these new barrels don't need some additional heat treatment as well. They certainly don't have the sophisticated patterns which are found in the antique high art barrels.
Guess I would consider either using an antique damascus barrel and freshing it up inside, or making a chemise of the antique barrel and putting in a modern steel interior. Teague in England is full length relining old barrels, damascus and steel, for a reasonable price. Might be the easiest and best route. Briley might be doing this work too.