What motors are in them? If you are after a V8 the 79 is the way to go since it will be a 302. The 80 V8s were 255s and like crazy aunts locked in the attic we don't like to talk about them much.
However if they are the early carbed turbo 2.3s it doesn't matter they'll both run like crap.
IMO the 80 body (Borrowed from the 79 Pace Car) is more attractive.
If they are 2.3s (Is that why you posted here?) Maybe retro fitting a F.I. 2.3 out of an 83 and up turbo Bird or
Stang would be worth it. Intercooled models can make 200+ to the wheels with ease. My SVO got 28 MPG (4.10 gears) and turned mid 13s at 108 or so on crappy street tires.