I look at 65-66 coupes for sale every day. To answer the question, I would say yes and no. What I mean is, naturally, as things do, they get more expensive based on inflation alone. That said, in my market, I have not observed a consistent, notable price jump. Dummies who over value their junk is a timeless constant.
The following examples are for cars that I would say are priced right, not this rusty $14k pipe dream. Nobody is paying that.
10 years ago lots of driver quality V8 cars were out there for +/- $10K. Now they're more like $12K. Today, a $14K coupe has shiny but not perfect paint, and needs little. There might be a bit of rust in the floor or trunk drop offs, but small stuff, nothing structural. $14-16K range is loaded with nice drivers.
I'm not an expert, but I play one on the internet.