FWIW, I have an old 180 series, '77 vintage I believe. And it shoots pretty doggone well! Years back I shot a couple of High Power Rifle matches with it, and did well, all things considered. It will hold 1-1/4" to 1-1/2" at 100 yds, if I do my part. From what I read, this 1 may be the exception, rather than the rule. :?
You can find manufacturing dates on Ruger's web site. If your son could get the seller down a bit, I wouldn't be scared.
When I got my 180 series, it had been shot almost exclusively with that nasty old Norinco ammo from the late '80's, early '90's. I was told it wouldn't shoot worth a damn, paid accordingly. :wink: It took me 3-4 days of soaking and scrubbing the bore to make it serviceable. And I'm more than happy with it!
Now mounting a scope on it, that would be another story! That's why we have ranch rifles, too. :lol: