The rifle was made before Savage came out with the short action model 10. So, in the case of the 223, you actually have a long action rifle, but there's a spacer so that it uses a 223-length internal magazine and there's an extension on the bolt's baffle so that the bolt only travels rearward enough for the 223 cartridge.
Personally, I wouldn't give that asking price though, as there's several places where you can get a new Savage with AccuTrigger for around $350. If the seller would drop the price another $50, then it might be worth it.