All of those dash pieces are interchangeable.
You can get dash pieces from 79-86 that will go on any of those cars.
I'd never pay $75 for those things though unless you were going to reconstruct an actual 79 Pace Car. That's retarded money for something with a little Pace Car badge. Otherwise that gauge cover looks the same as the one in my 83 (minus the silver trim). Check the junk yards man. You'd be surprised what you can find for $2.00 sometimes.