Agree with the above ^^^, this is a desirable touring bike. The frame will have all of the braze-ons and features you'd want. The LBS location is to the buyer's advantage, as the collector visibility into this bike will be very limited to walk-in customers.

That said, I'd want SunTour barcons and Nitto Randonneur bars on it, along with original DiaCompe levers. As someone noted above, conversion to 700c will be problemmatic, as I think that the calipers are DiaCompe 981's, too short for correct 700c use. You'll have to stick with the black anodized 27s. Throw out the Tourney and find a period SunTour derailleur, like the Cyclone MkII...

Anyway, I'd buy the bike at $300 as is. For the full price, I'd at least want the proper period parts for it. Time to negotiate...