As far as I know, you would have to change the front apron to use the later hood on an earlier car. The later hoods are shorter because of the different bumpers.
As long as the part of the hood that meets the windshield area fits, it's all set. I'm not running any sort of lower apron anyway, just sort of a pin-on bracket.
if you use a 72 hood on a 67 or 66, i dont think it will work even if you change the front apron cause the curve near the windshield is different-I think?also the 66-67 hood are narrower. if you need a 66 or 67 hood -i have a nice one for sale.