[TheSilverBuick]

Definitely a multi-faceted issue. IMO, a big issue is the junkyard source of hard parts is about dried up. No more local yard to pull "slightly" better seats, door panels, body parts etc are out there in high quantities. Same with engines, etc for that matter. So building these cars, if it needs something, the reproduction stuff is pricey. In the 90's I loved going to the junkyard looking for parts to put on my cars. I haven't seen more than two car's out of the 70's at once in the junkyard in years, let alone a 60's era vehicle.

I'm personally a fan of modernizing the old cars while retaining the exterior sheet metal look. I personally like matching engine make to car make, and modernize the dinosaur engine, but completely get the economics of a modern drivetrain swap. My old Buick has a roller cam/rockers 455 with multiport EFI, distributorless ignition, etc. and the same treatment to my Pontiac OHC L6 plus turbo. I can get ign coils, pumps, fuel injectors (that will work in a pinch), and sensors at about any auto parts store. Far easier than getting points these days! Let alone a correct Q-jet rebuild kit or mechanical fuel pump. I'm converting a thunderbird to electric, so that'll be an interesting case if fuel goes through the roof or worse, but the exterior will be OE sheet metal and interior mostly left OE.