I have a M77 mark II target in 223 remington and my brother has one just like the one you looked at but in 30-06.
I had a problem with the locking lugs and the controled round feed when I got mine.The lugs looked like they had sand in them for years and the lock up was ruff.The controled round feed would not catch the bullet when it came out of the magazine.I sent the rifle back to Ruger and they fixed the feeding problem but did nothing for the locking lugs.i had to take a fine stone and some JB bore past to them and fixed that problem.
My brothers rifle was in better shape but we still polished up the locking lugs and has a real smoth action now.
Both rifles shoot real well and have had no other problems.I love the scope rings I think there the best out there.As for the price I think its a little hi my brother paid $450 about two years ago but i think the price has gone up since then.
If i had to do it all over again I would still buy the rifle.I think you could do a lot worse than the deal you got going.