I haven't shot anything that light other than 85 gainers for fire forming my .260ai, but have lots of experience with 140's up to the 156's. Rl26 might get you what your looking for as far as speed, I am lightly compressed with my 156's at 49.0 grains rl26, they are going 2940 fps from my 29" barrel. I used H4831sc with the 140 bergers and they were ridiculously accurate, but shot best at 2930, maxed out around 3000 fps, even in the long barrel. Rl26 got me 3120 before I had the same max pressure signs, I ran the 140's at 3070 with rl26 for a while. Then transitioned to hornady 147's, they were running 3040 where they shot best, max was about 3080, and then switched to 156 bergers, which max out around 3000, and shoot best at 2940.
For the lighter bullets, RL23 might be an interesting option, I haven't tried it though. But considering it's a little faster burn rate than rl26, temp stable, and should get great velocities....that would probably be my first attempt.