H4895 can be splendid in the .25/06.
It will still give .257Roberts speeds and top accuracy.
Consult several manuals and start 10% low like with any powder.
I suggest trying 100gr bullets. You'll be able to get 3,100fps w/max loads.
My Hornady #3 manual has H4895 DATA.
43.0 MAX W/120gr 2,900fps
44.0 w/117 2,900
44.5 w/100 3,100
46.0 w/87 3,400
49.5 w/75 3,500
Use CAUTION with this data. I rounded down to nearest 1/2gr charges and they are from a circa 1980 manual.