The 280 AI is a great choice. I have considered it myself since I have 3 friends who have had the calibre built into an old 30-06 action.
The cartridge seams to be friendly to all sorts of powders and has surprised us with some unexpected high performance.
My one pal Mike has a 25 inch barrel with the last inch ported. It seems to be just enough to settle the rifle down and his 150 grain Combined Technology Silvertips are coming out of his barrel at 3010 pushed by 61 grains of RL22 and a Remington match primer.
I found a source for steel recoil lugs for the Tikka action and have included it below. I think it will be an improvement from the aluminum factory piece.
Kinetic Research Group, ltd (KRG)