Re-lining barrels was common back in the day. Drill/ream the barrel, and insert a liner. Brownells still sells the liners I think. Those old guns suffered more from corrosion and pitting than actually wearing out the throat as we know today. I know some black powder competitors that went 20000+ rounds. A lifetimes worth of use for an average joe in those rifles (BPCR). There is a guy in Texas, who’s name escapes me, who does what the op is asking. Not that common for sure. What missed is saying about hard throats seems right, if not only for the material, but the carbon buildup, which is super hard.
OP, ask yourself honestly how much you’ll shoot. Do the 6 creed and enjoy it. If the barrel life gives you that much pause, do the 6.5. There’s a click or two of difference between them. Nothing lost either way imo.