I've loaded for three different Rem 7mm08s for the past 30 years. With 140 grain bullets, IMR4064 was the ticket for two of them. H414 (W760) was the winner for the third.
Having said that, I've recently, for the rifles that preferred IMR 4064, changed powder. Using the current max charges listed for IMR 4064 as a guideline (as much as 5 full grains lower than Sierra's manual from the early '90s!!!), I just can't get the velocities I seek using IMR 4064 in this cartridge (low 2600s to barely over 2700 fps). YMMV.
I've recently worked up an accurate 2800 fps load for one of the two using 139 gr Hornady Interlocks and Varget.
Of the powders listed, I'd start with Varget.
