Boomer - unless your .270 WSM is ailing - there's no reason you can't make that 500 yard shot from the blind with your factory rifle. It's a flat shooting cartridge with an excellent reputation for accuracy, and should make short work of a deer at 500 yards.
Of course, if you just want a cool new Krieger barrel on the rifle - I fully understand that!
I don't think you're going to gain all that much velocity from an additional 2" of barrel length though.
Two of my hunting rifles have varmint weight, or nearly varmint weight barrels: a .308 Win/Rem 700 with a 24" Krieger turned to the Remington varmint contour and a .300 WSM/Win 70 "Coyote" which still has the factory 24" stainless barrel. They're both a little heavy for general purpose hunting, although I've backpacked and hiked with each of them. Either one is easily capable of 500 yard shots, the .308 in particular exhibits very good accuracy out at 500 & 600 yards. It's gone through a few barrels now, and I keep coming back to the same contour.
Someday I'm going to need to re-barrel the .300 WSM too - and like you I've considered going longer and perhaps even heavier - but I don't think I'm going to do so. It's heavy enough for excellent stability.
Take your time, consider the intended purpose of your rifle. If it's purely for shooting from a blind, a little extra weight isn't going to be a problem. If you intend on doing some mountain hiking with it, or even anticipate a possible snap shot while walking to the blind, then a heavy barrel is going to be a bit of a drawback. It's all about trade-offs.
.300 WSM Model 70 Coyote on a backpack hunt in the Cascades. The laminated stock and slightly heavy contour barrel make it a bit of a chore for packing, but it does shoot well:
My ol' "Green Machine" .308 Win/Rem 700 - the center-fire rifle I shoot the most. Broke it out for whitetail hunting this year, and shot this little fellow from a blind. He was only 75 yards away, but I was scanning an area out to nearly 500 yards while in the blind:
These two are a tad heavy for general purpose hunting, but the extra weight is nice for stability when making a longer/precision shot. I've actually done pretty well in 600 yard prone (not F-Class) matches with the .308 too.
Don't be in a big hurry - figure out what you want before making the decision. Can you hit well with the factory rifle at 500 yards? Perhaps! It's really not that hard, particularly from a steady rest.
Best of luck - I like your project - it's got a specific goal. Deer at 500, from a blind. Cool.
Guy