Shilen here in Texas has a great name for barrels.
Douglas, Hart, Schneider, are some others.
MidwayUSA catalog has a lot of brands. Also see Brownell's.
700 action is a great action. Polishing, truing, and coating the bolt/action is one thing. Replacing? Why? 700 Action is used on yany high-dollar custom rifles. See Sisk.
Barrels come in variety of stages of finish. Even if the barrel is completely machined, it needs to have headspace checked. Should be able to find a factory replacement barrel.
For 7mm Mag, 1:9.5in twist is common. I looked through Midway Catalog, there were some with different twists. The 180gr match bullet recommends a tighter twist, can't remember if it was 1:8.5 or 1:9. I think Sierra makes the bullet. I have also seen 1:10 twist barrel for 7mm Mag.
IMHO: 160-168gr is perfect for 1:9.5 twist Rem. 7mm Mag. Somebody makes a 145gr match bullet, but that may be for 7-08 or 7x57.
I wonder if the Sendero barrel would work. It is heavier than the SPS, but it is fluted.
If you go on some of the bench rest shooter's sites, they may have some slightly used barrels that are of very high quality.
I think you'll find picking up a Sendero II in 7mm Mag is cheaper than a heavy customization of your SPS.
Some of the new SPS offer the X-Mark Pro trigger.
