I can't say I know enough about them, but I figure as long as you are equipped to rechamber the breech, contour the barrel, and reload for a .308 bullet, you should be golden.
I would imagine that these would be like the UK 59 barrels that came out a few years back. They were a deal if you were able to do the work yourself. If you had to hire a gunsmith, they needed a lot of time put into them and ended up being quite expensive to make them shooters.
Apex gun parts sells a machine gun barrel that is already chambered for 7.62x54R with a .311 bore. However, they are off of a gas operated rifle so you would have to plug the port and still do all the extra work too.
Every snowflake is unique. There are uncountable grains of sand on the beach. Mosin-Nagants are like sandy snowflakes. You’ll never get all the ones you want.