J. Solo: I would expect the rifling on that Marlin to look shallow - even with Ballard rifling, which at todays standards would also have to be used for jacketed bullets, I wouldn't expect a modern cartridge barrel to have rifling more than .002 deep.
As far as those rifling marks in the barrel are concerned - as big medicine said, thake it out and shoot it. But, if his rifle takes about 20-25 rounds to get back into its accuracy after a good cleaning then I think the both of ya should firelap those barrels.
Once I firelapped mine, my accuracy was consistent from one session to the next. It sounds like there is enough roughness in both bores to take some copper jacket buildup before the roughness stops affecting accuracy.
When big medicine said that after a couple of hundred rounds the bore will look better, then you need to know that after proper firelapping your bore will look like a mirror and shoot like never before. HTH. Mikey.