Hmmm...

I get the love of nostalgia, but some of the pre-mid-1970's bicycles had stamped lug frames. That was a very weak frame and prone to poor welding too.

Nishiki and Batavus began importing better bicycles into America about this time. They were much stronger bicycles versus say an old Schwinn.

I don't know, but I would think that any old bikes would have to be totally restored mechanically from tremendous wear. Even a bike that's two years old can be abused.

On the other hand, sometimes one can pick up a very good mountain bike from some place that caters to tourists, do some minor repairs, and have a bike for about half the cost.

Restoring an old bike with authentic parts from prior days with their heavier frames, well doesn't make a lot of sense to me, but if you have endless money to burn, whatever floats your boat.

A lot of technology occurred since those early days with composite materials.