Necking down the .308 to 7mm-08 is easy. I've never had a problem with mixing up the brass. I do, however keep them in 50rd plastic boxes with caliber/cartridge clearly marked and color coded (ie:all my 7mm08 are in Red boxes (like the Nosler ballistic tips). (ie: .257's are in blue) and .260's are in "smoke" colored...ect.).
I do match them up in same headstamps (ie: all my 7mm08 are in Federal, Remington, or Winchester brass.... and sorted likewise.). (All my .260Rem are in PPU .243 brass...).
I really, really like Reloader17 in the 7mm08. If you need data, you can essentially substitute RL17 for IMR4350. Velocities will be close to, or slightly higher than H4350.
I'm loading 48.0gr of RL17 under the Hornady 139gr BtSpt for 2,900fps (20"bbl !!!).
46.0 under a 150gr bullet for 2,800fps. Accuracy is as good or better than IMR4350 which has proven to be best powder from my rifle for accuracy. Never have gotten decent accuracy with Varget, IMR4064, H380, or H414.... My rifle is "very, very particular" about what it shoots well. It much prefers slower extruded powders..... And pressures below factory level for good accuracy.