Like others have posted, with antelope, accuracy is more important than bullet energy. With a .308 Win, I would use whatever 150 grain bullet that was most accurate in my rifle.

I have hunted antelope most years for the past 45 or so years. My favorite rifle is my .257 Roberts Improved shooting 115 grain Nosler Ballistic Tips, 117 grain Sierra GameKings, or 120 grain Hornady Hollow Point bullets.