I have no idea what stock rifles are chambered in 280ai or what your budget is. I do know @p_ham just opened his books back up for new work. He is a FFL dealer and can get you a new 280 and cut the AI.
I would have to imagine that the major manufacturers all have a 280.
Every Browning I've played with has shot extremely well. I'm an AI fan. I did as above a long time ago. Took a 700 mountain rifle in 280 Rem and had a local smith true up the action, set the barrel back a tickle, and recut the chamber to AI. I also like hammer bullets, but I have not moved this one over to them yet. I have too many Barnes on hand to just switch over. 145 LRX at 3050 out of a 22" barrel. Have fun!