NZ,
It's your car, do to it as you wish. There are things about each year that I really like and I'll never hesitate to swap parts from different years. I really like the twin headlight look, the gills (was going to put them on my 69 cuda), the shaker or powerbulge hoods, but I love the round tail lights. Call me weird but that's my taste.
I'll never try to pawn it off as anything other than what Ma Mopar intended it to be though. All vin numbers and stamps will be as they were when it left the factory.
Bottom line is that cuda's are cool no matter what year. Some are just a little more original than others.