Pretty sure the Faxon gunner barrels have a 0.625 gas journal. You’d need a 0.75 in order to use the Siberian gas block. You also need to make sure it’s a mid length gas system for the piston to be reused.
Best bet would be to organize a group buy with a domestic supplier. If it could be maintained at 2lbs and there were enough interest to keep costs at about $400 a barrel, I think it would be possible. I’m going to be measuring the weight and size of the gas hole on the factory barrel today. I’ll post the results