Lots of guys on here can and will direct you on barrel, action, stock, etc... way better than me. For caliber: a lot of these, let's call em unique calibers, are great, but your uncle isn't going to find a case of SAUM ammo most anywhere and all the RUMs are about the same (and imho, no better than any WBY round, actually not as good) - I have never seen much 26, 28 30, 33 Nosler ammo on any shelves, but for what you have described and today's technology and offerings, a 300 Win w/brake is a greatthe solution. For what you have described, I use a 264 Win, 300Win, 300 Wby and 340Wby and the only one of those it is hard to find ammo for from the factory is the 340. There is actually plenty of it out there, you just won't find it at mom and pops and I almost never see it at cabela's or Sportsmen's either. Best of luck.