Re: 7mm-08 Short or Long Action build
The Rem SA isn't long enough to take advantage of the heavier bullets in 7mm, unless you plan on single feeding. Moving to the Savage LA also gives you more options as far as cases go, but the 7mm-08 is quite capable out to very extended ranges. Most of the benefit will come from what barrel you choose and how you have your barrel done for you.
FWIW, my 7mm-08 is done on a Savage SA DBM (centerfeed) with a 26" Shilen barrel with a 1-8" twist. After I got dialed in, I was shooting very accurately to one mile using 168 Bergers and JLK's and 180 Bergers. This fall I plan to shoot with those guys again and will be using Sierra 175 and 180 SMK's. With the SMK's I'm running about 29-30 moa to get to 1k. Note: Rem 700 SA will allow a 2.800" cartridge OAL. My Savage allows a 3.2". That .4" is a huge deal with what you can load and how you can load it in the rifle.
As far as more potent rounds go, it's simply a matter of how much recoil you're willing to put up with vs. reduction in elevation/wind drift and reduction in barrel life. Not loading high pressure loads in my 7mm-08 has it looking near new after about 1200 rounds. I've also found it tough to beat a good shooter who has a hot-rod round in the same caliber as you. There are plus's and minus's to both.