Shane,
Most Marlin lever action rifles are proofmarked at the factory with a "JM" stamped over the chamber area.
The modern Marlins I've seen are proof stamped on the left side in 1/16" letters. Marlin factory barrel markings include address, model, caliber (left side), and WARNING markings (right side).
A re-barrel would not have this marking. Plus, all factory Marlin lever rifles have front and rear sights.
The .40-65 case is based on the .30-40 Krag case rim/head size. BPCR shooters like it for mild recoil and good wind bucking for long range.
Marlin started using the crossbolt safety in the late 1980's, I think. The M1895 action is based on the M336, but with ejection port and bolt face/extractor opened up for the big .45-70 case rim. If your ejection port can handle a factory .45-70 cartridge, that confirms it was rebarreled from an M1895 .45-70. If if doesn't it was probably made from an M1895 .444 Marlin.
HTH
John