Of course it's possible to get any diameter bore you want.
I have a buddy, that relieved one to 45-70. At first, I thought he was crazy. He had a barrel and a receiver, as well as the original stock. It turned out very well.
With the 20 inch barrel, it was a very handy bush rifle. He also modified the bolt handle, by sweeping it down and extending it. With the addition of decent orofice style rear sight and a large blade front sight, it was very quick to aquire a good sight picture on targets, out to 150 yards.
The actions, leave much to be desired but if you have the time and know how, they can be adapted, fairly easily, to just about any rimmed cartridge that is close to the original rim diameter of the 7.62x54. There were even some converted to 30-06. The only problem with them was that the barrels weren't set back far enough to clean up the chambers and the bolt faces weren't altered to support the case head.
I've also seen several of them converted to 303 British. That is very simple, just set the barrel back enough to clean up the chamber, with the sights on top, and head space. There was a time, when the rifles first came into Canada, back in the late sixties, when you couldn't buy any ammunition for them, so many were converted to 303British. Same thing happened to a lot of SVT 38 and 40 rifles. Not the thing to do if you are a collector but if you just want to shoot or hunt with them and you like the actions, it was a good option and cheap.