You don't reline for high pressure cartridges. After the chamber is cut there won't be any thickness left to the liner. A rebarrel is not a big deal, and would be the way to go in this case.
Funny, I am in the same boat - I have a Savage 1899 that was originally a 30-30, and at some point got rechambered to 300 Savage. But the bolt and magazine are still original, and it really doesn't work right as a 300 Sav. So I am going to build a new barrel for it, and am wrestling with the option of 30-30 or 25-35. I have the 30-30 reamer on hand, but a 25-35 sounds like it would be a neat trick so I haven't decided yet.
Making a barrel for your Marlin would be nothing difficult, just takes more time than a bolt gun barrel because of the way the breech is machined and adding the dovetail and sight cuts. But otherwise everything else would stay the same.