I'm going to get out the crystal ball and predict that somewhere in the near future a car like this will not seem overpriced at that number. Assuming it is a rust free original sheet metal car that could be easily 'massaged' with engine/trans upgrades...it's really not too crazy.
I see lots of $15k rusty Chevelles that need $15-20k worth of body work and paint...and interior work besides. When you add it all up, these low mileage granny style cars are the best ones to buy.
Now is $40k a lot today...probably, but a year or two from now it will be different..remember folks next year those 70 Chevelles will be 50 years old