Not having original equipment wouldn't be a deal killer for me, but the negotiation would be far from over. I'd be telling that mutt, "look here, I'm buying a frame, it would be worth more to me as a bare frame to keep from having to take all this crap off" and just not mention I've been kinda looking for a DX groupset. capisce? Note those vintage Ritchey stems with the little basket are horrifyingly expensive, if that's still on the bike that would be a plus. Rims just kinda are what they are, there's been a bunch of NOS Ritchey Vantage rims on ebay lately for a good price, but if the rims are beat (and they probably are) that too could be a good talking point
If the dude didn't want to get beat up on price, he wouldn'ta asked a thousand bucks for that thing, so go beat him up. Flip side is, the way bicycle restoration works, $50 one way or the other for a frame is a drop in the bucket. If the frame is sound (not all out of alignment, seat post isn't stuck, no pitting rust, and it's really a Ritchey) you can't go too wrong from here