I could go on for hours with you as to the collectibility of the old cars, what affects value, how much it affects value etc.
After I am done, someone else will spend hours with you and give you completely different information.
The car you are looking at is not going to be a "collectible" car because the motor is the wrong year. I have a 68 Firebird Convertible that I owned for the last 28 years. The motor is a 68 350 2bbl. The car left the factory with a 68 350 2bbl. How does that affect value?
There are too many factors to consider. What you are looking at is probably a nice number 3 car. Not a 1 because of the motor, not a 2 because there are probably a few chips here and there, and the excellent interior is probably not perfect.
The prices of late 60s muscle and pony "drivers" has doubled in the last 7 years. I have my 68 up for sale because I don't use it, and want to DE my Porsche. there isnt enough time to finish a restoration, DE, and play with the baby.
The bottom front of the doors is a rust spot, the bottom of the rear quarter is a rust spot, the floorpans are rust spots. corners of windows, and the list goes on. how is the endura front bumper? which transmission?