You are better off to buy a trashed chrome bumper car, and your later model C3. Then, put the frame and interior out of the newer one into the older one.
Otherwise, you are talking about cutting the entire front clip from the windshield forward, and the entire rear clip from the door lock post backwards to do this. Plus, the chome, brackets, etc.
Yes, it could be done, and has been done. If you had all the parts around and about, you could pull it off, no doubt. The cost would be over the top though if you had to buy all the parts new and vintage and start from scratch.