Both Hodgdon #26 and #27 list 60 grains of H1000 as the maximum for a 162 grain bullet in the .280 Remington. I was thinking a 60 grain starting load and working up toward 64 grains watching for signs of excessive pressure.
Jakcfish, Experience says that H-1000 is a little too slow for the 280 AI. I think if you try H-4831 or IMR 7828, you'll like the results a little better. If you want to use H-1000, I've gotten the most favorable results using a CCI LRM Primer and 60.5 grains. Shooting Parition bullets and RP brass. Cases were sized, trimmed .010 under max. One note that I have in here is that after 9 firings the cases were still under max in length and showed no signs of wear.