Saving a nearly lost car

I have a 1975 dodge dart 2 door shell. The car was rear ended so most of the back section is junk. Over the years a piece here and a piece have disappeared from the car as I have given a lot of parts away. The car still has a title.

Next to it, I have a 1968 dodge dart 2 door shell with a perfect body and most of its parts left that I was saving as spare parts for my other darts. There is no title on this car.

Well, someone suggested to me that I combine the two cars and make one. That is a great idea except for the fact that final product will look like a 68 because the majority of parts I have are 68.....but the core of the car will be the 75 and obviously the vin number will read LH23C5B for a 75 because that is the only title I have.

Problem is and question is: how can I combine these two cars and keep proof that's its not a re-body but in fact a legit car built from salvaged spare parts. Because the core shell will remain as the 75 (as per the vin) because the 75 is a more solid shell minus the rear panel damage anyway.

I don't intend to sell it as anything its not but actually I was planning to give it to a little cousin as a first ride and she is not picky.

But will it look weird to have a car that looks like a 68 on the outside but the vin and core is a 75?