I had a friend, collects militaries, was trying to figure out how many Mauser rifles had been made. Stopped at 100 million. (Many, many varities, but...) Point is that no other gun has been made in those numbers. SO it is easy to find "Mauser" anything and less likely to find any thing else.
You have to ask. Sure the barrel manufacturers make barrels and no doubt thread/chamber a few for about anything you can name, but find it at K-mart or advertised? NAW!!!
Benchrest.com has the top line barrel makers who choose to advertise there. Email them. They just might have a barrel gathering dust in what you want. Might not. As said, MOST correctly, any blank can be threaded and chambered for your action. (I own/love several P-14s, the original .303 Brit version.) It is a heavy action. Maybe not the strongest with all the improvements since WW I... but very serviceable. Just don't expect FREE.
Buddy, retired gunsmith told me of one that had been rechambered/barreled to .22/250. NO magazine work. If you got excited (in the prairie dog wars) and closed the bolt fast the cartridge would jump over the front ring and out of the gun completely. !! Great piece of history. Weight more suited to heavy magnum rounds, but it is yours. Hit the barrel makers. I would bet they might have something and .25/06 is from that era. But you will have to dig. It is just like finding pontiac parts. Chevy is huge. Parts everywhere. Pontiac, you got to ask. LUCK.