A .270 would ve perfect. Kind of unusual to see a bull barrel in that caliber - it never caught on as any kind of a competitive match round, nor as a varmint round. Not many "match" bullets out there in that caliber. It's really not all that expensive to get it turned down a bit, if he wants a lighter rifle.
I'm starting to like your daughter more and more. She clearly has fine taste, and a good head on her shoulders. She should talk to her brother more...
I've always thought Marlin lever guns superior to Winchesters. I've had a few of each, in many different configurations. Still do. Winchester makes what I believe to be the all-time best bolt gun ever made, in the pre-'64 Model 70, and the later USRA produced "classic" reintroduction of it. Yes, their lever guns are considered "classic", more so than the Marlins, but the Marlins are just better in many ways. She couldn't go wrong with a nice 1895...