Well it is an 03 sporter, and the serial number is high enough to make it safe to shoot. Is it worth $300? Probably, but I'd try to get it for less as it needs more work IMO. I'd probably take a chance on it.
The military safety will not work with a scope mounted in low or medium rings, probably still has the old military trigger the can be either good or bad. No telling from the pics what kind of shape the stock is really in or condition of the barrel. However, it does appear to be a serviceable rifle, that with a little work would serve well as a slayer of moose.