I don't gun hunt much, more of a bow hunter. But I went with a 30-06 for it's versatility. Nothing to extraordinary just a Ruger M77 MKII, glass bedded it / floated barrel, topped with a Burris Fullfield 4.5-14 x 42mm. After dialing in a hand load I have a rifle that's more accurate than I can shoot it. I can get 3 rounds into 3/4" at 100yds consistently off a bench and I'm sure a better shooter could shrink that. And that's a 165gr spbt with a hot load and serious recoil. Since you already have a 270 and 300mag I would recommend spending the money on reloading equipment rather than another rifle. You can fine tune a load that will give you a balance of power and the level of recoil your father is comfortable with. Reloading isn't difficult once you take some time to read up on it and ask a few questions.