Hmmm. Looks clean and I think the sellers description is honest. Shimano 600 is good stuff, it's called Ultegra today and is #2 behind DuraAce. Of course it's not like current drivetrains but should function very well.

The thing about used bikes is that $ value is very relative. Somebody found, or will find, a bike just like it for $10. Checkout the "Catch of the Day" thread. If the seller had given it to charity Goodwill or whoever might have sold it for $25.

OTOH for less than $300 you've got yourself a high quality roadbike that is much superior to anything new in its price range or even for $100 more.

If you ride it alot it will be worth the price paid and more, that's for sure.