CZ makes a bolt action 7.62x39, so that is a pretty easy place to start.
For the 54R, I can't think of anything that would be easy, because of the bolt work for the rimmed case, and the lack of quality barrels that are .310-.311" bore size, instead of the more traditional .308".
And don't take this the wrong way, but is really not a smart thing to do. It doesn't offer anything over cartridges that have been introduced in the 125 years that have passed since its introduction, except maybe cheap ammo (and that has pretty much dried up). The Russian rounds have a larger bore than US .30 cal rifles, so the selection of quality bullets and loaded ammo is much lower.
Currently 7.62x54r is damn near the price of cheap 308 ammo.
You will be spending extra money to get less performance and.
What is your intended use for these rifles?
I also just noticed, autocorrect screwed me, my post on rechambering should have said "the old cartridges needs to be smaller than the new". Not smarter.