As far as I am aware Walther make a model A contour copy that I have read is supposed to be a copy of the 404 or the 10.75 x 68 tube dimensions. I rebarreled a small ring mauser, brno 21 with one and it is an excellent weight for a 9.3x62. But this doesn't help you make your decision....

Surely your safest way forward is to find a U.S manufacturer that makes 9.3 tubes and have them copy your contour. I know Lilja do a 9.3mm x 12" twist-(perfect) and will make any contour you want for $35.00. I would ring Lilja and see if you can send him your existing tube and have him measure it up and load the dimensions into his CNC lathe, copy it exactly and be happy. I dont think you will find an easier way forward. If you want a cut rifle barrel Dan Petersen might be worth a try. He has a copy lathe that can copy the contour of your barrel via a stylus. Either of these ideas should get you what you need. I would not do the Walther option as there will be no guarantees as to what you get dimensionally.