In my sample of one SPS(early 90's vintage), I see no reason to upgrade. It's a heavy old plastic stock though, maybe the newer one's are more flimsy?
I never carry the rifle, just gets hauled around by a horse for 3 or 4 days every year.
You may want to get a nicer stock if it's gonna be a rifle that you use alot. Beater gun and I'd leave as is so long as it held POI.
This is going to be a scabbard gun (to replace a Model 70 in .300 Weatherby), but I usually guide in areas above where we can ride horseback, so I'm going to be draggin this thing up the side of many mountains in horrible terrain.
I live in the middle of the largest burn in Colorado history so we hunt in nasty terrain with looong shots as a norm.
I'd like to build something that could endure this type of hunting with the appropriate caliber for the type of shots.