As someone who grew up in the early '80s and who still keeps and rides vintage '80s bikes, I would have no interest in something this old. Most of my collecting buddies are the same, bikes from the '80s on up. And even then, most including myself are at the age where we are starting to thin the herds and modify those we keep with modern components to be able to enjoy them more as we age. It is just a fact of life, the collecting pool for these old bikes gets smaller and those that enter the market fresh, have a hard time paying what we think they are worth. As the market gets worse, I don't see this changing.
Onto this bike, I know what it costs to restore frames and source period correct components, and the only way I'd take on something similar to this, say a bike with incomplete group and finish issues, i.e., rust and missing paint, is to get it very cheap or it was something that I lusted after as a kid. I see these dollar amounts being offered up for what it is worth and I just can't wrap my head around it personally. But again, I am not the market for this bike but those who are, are even older than me and I can't see them taking on more costly projects at their age unless they could get it very cheap, not $1500-$2000. My one acquaintance who is the market for this bike is 15 years older than me and has all but given up most of his '60s-'70s collection and now focuses on keeping in relatively decent shape riding his modern upright bikes and only the best of his collection remains, which are pretty much museum quality wall hangers or taken out on easy Sunday rides. I'll be at this point in 10-15 years God willing and then the market will be flooded with vintage '80s bikes and I'll have to practically give them away at that point.
Good luck with whatever you decide to do with this bike and I hope you find the person out there who truly values this era and it goes to a good home and you make a nice profit on it. At least it has a chance of going to a collector now and not the dump.