I have a 20-inch BLR in 7mm-08 and an 20-inch Model 70 Compact in 7mm-08. I prefer more weight and less muzzle blast than barrels shorter than 20 inches have. Velocity loss in the 7mm-08 is not much, so going to a 21 or 22 inch barrel should be all about balance and feel for you, not 50 fps.
As stated, the 139-140 grain bullets are the norm. 150s and 154s will start to lose steam with the smaller case and shorter barrels. 160-gr is really in the domain of the .280 Rem, .284 Win and 7x64mm.
For flat shooting to 300 yards, go to the 120-gr BT or TSX.
It is hard to find a Steyr that won't shoot well, and like the Tikka T3, they aren't picky about various loads.
