Your stated difference is about right with factory loads. We need to remember that WSM pressures run higher than 25-06 & belted mag. rounds, part of a way to sell the new rounds. So, if you buy factory you
would be looking at about 150-200FPS difference & if you don't reload it
is a factor to consider, however for the subject of Antelope & Deer it is
mainly academic.
However, if you reload to equal pressures these two with the stated bullets will be within 100FPS & that is the ONLY ammo I shoot. With my 25-06AI with 125 Wildcats, it is a little flatter than any available 270WSM 140,
& with the long shank the energy is close indeed.