Re: Rechambering Dilemma
Don't forget about the bolt face diameter differences. You will need to fit or have fitted a different Savage Bolt Head to accommodate a magnum rim diameter. Not anything major, but it is an added expense, and there are a couple of versions out there, depending on the rifle's age, and it pays to know which is what. Barrel contour also has to fit into the existing channel.
My suggestion would be to hold onto the barrel, You are tired of the 7-08 now, but that may not always be the case. Nice to have the old barrel to fall back on. Magnums can get old.
Instead of selling or rechambering, I'd try for a prefit barrel. If you keep with cases that employ a .473" diameter cartidge base, you'll save on the bolt head coversion. Be aware that .308 based cases cannot just be rechambered for the .30-'06 based cases; the .308's shoulder diameter is wider than the .30-'06 case at the same height above the base. The barrel must be shortened several inches before this can work, and that may end up being too short for good efficiency.
The .284 Win and 280 Rem both use the same bolt face as the 7-08. The fired .280 case will extract and eject in a short action, but won't fit into the magazine and will need the bolt release to be tripped to extract a loaded round (which happens seldom enough to make it worth using the .280 Rem as a single shot action for comp/target shooting). In essence a .280 rem is a 7mm-'06, and is plenty adequate for 1000yd work.
A 1:9" twist will work for 168's and maybe for 175's, but longer bullets need a faster twist, or so I'm told. The .280 Rem will drive a Nosler 150gr BT to 1000yd supersonic without too much trouble. Gets the job done without the customary ripsnortin' magnum whackage, if if you consider that's a point worth considering. I do.
If you're going with a prefit, you're not limited to a 7mm bore.
Here are some prefit choices with prices from Lothar-Walther USA. A Savage Varmint Contour is an available option for L-W prefit barrels. Honestly, if the cost of a new barrel is a deal breaker, maybe it's not the best time for a caliber swap.
Greg