Given what I found with RL26 in my 270 MT and 150's, I'd absolutely go with the 61.5 gr load and not look back... and I'm a darned conservative handloader.

My guess is the "standard" 280 would run a 160 at 3,000 from a 24" bbl with RL26 at max, but safe pressure.

I truly don't believe you're over max, or necessarily even at max.

“Perfection is Achieved Not When There Is Nothing More to Add, But When There Is Nothing Left to Take Away” Antoine de Saint-Exupery