Wow, can't believe that no one replied to this one. There are LOTS of miracle finishes guns today. Diamond Coat, DuraCoat, the finishes by Robar, the various teflons....
The process of preparations is actually more important the actual finish itself. If the metal isn't prepped right, the finish isn't going to last. Robar is HIGH quality finishes for law enforcement, military, and competition, and prices are pretty good too.
Lauer Custom Weaponry is the maker of the DuraCoat finishes, and they developed them for military applications as well. I would go with either one of those two companies more than likely, but I'd also take a look at Brockman Custom Rifles website, they specialize in custom Marlin lever actions, stocks, uupgrades, and finishes. Wild West Guns in Alaska is another good company for Marlin work, but unless you live in Alaska, turn-around times may be a bit lengthy.