Good advice, if you have some IMR 4064 I'd try some. 4350 is a staple for many bullets in the 260. Varget shot great in a former 7/08 w/100s, as well as 120 and 140s, may well be a good one also.
4895, RL15, and Benchmark mentioned above also good ones.
If me, I'd settle on a 120 BT for Antelope and deer if you want one bullet, but rather a 125 Partition, a 140 of your choice, or a 120 Barnes on Bear, the 129 SP is a great all around bullet as well.
I think better accuracy would give the heavier bullets my choice, not changing POI for other game. If you have 100s now try the above powders.
The Barnes are great bullets, but if you shoot far out w/a mono bullet, the expansion may not be best on a small animal like antelope IMO. I'd go for shoulder shots if you do.
FWIW, the 130 AB is my go to for everything in 260, I'd shoot Mice to Moose w/it
