I'm not a young man and have owned many 22's over the years. Yes, NRL base class especially if you want to really compete must be new enough to have MSRP available. As I understand a number of guns compete in all classes. The 77/22 is not known for it's low MSRP. Besides cost you need to know you are competing against guns that will shoot inside 1/2" at 50 yards, some more like 1/4", even in base class. I'm sure you can bring what you have and enjoy, even if you shoot open to minimize initial costs. As with most competitions you learn more by doing than reading and can save some costs if you shoot first.
I don't currently have a magazine fed gun to use. My XXII is an amazing gun but don't want to put a big tactical optic on it and bang that beautiful wood stock around. My 10/22 has a Kidd lightweight barrel and for this game I think you want weight to help settle the gun in position.
From my research Savage Mkii will do, and I do love my Savages, but with Diamondback tactical you can spend more on the gun than the Savage MSRP so I am buying a Tikka T1x. CZ 457 also have great reputation but I like that Tikka has factory stock mods to make a more vertical grip and a wider forend that are legal. I would also suggest you visit some of your local NRL matches to see how far they really shoot. Canted scope bases are often needed to get to extended ranges but that cant combined with available scope adjustment can also set you up for not being able to zero on main reticle at 25/50 yards. I have run into this on LR centerfire rigs. If your local matches only shoot to 200 yards should not be a problem. I don't have a lot of local ranges that go past 200 and the NRL near me does not.
I hope that helps.
JB