I've never understood this, once the original block is gone that's it, it's no longer a numbers match car. Maybe this something the corvette peddlers started in the 80's when Mopars started getting hot investment wise.
It's a way for people with extremely rare cars to still justify their Sticker price. Just like that GYC Challenger that put them on the Map and the non original Drivetrain. Because they think it's OK it turns into a cult following and next thing you know it's the new "Thing."
But one could argue the first time you change the oil it's no longer original so people will have different opinions. Mine is if I'm paying some hideous price for a car with a OEM type attempt at being restored it better have the main components from when it rolled off the assembly line or no deal. Otherwise go buy something else and build your own...
