I don't think we have a 'wanted' section. I would post in the appropriate forum for the car you want. They'd be the best people to ask.
Do you want one of them or do you want the one you had?
Go to shows, ask questions, talk to local Cadillac club members, talk to local dealers, look in want adds, eBay, craigslist, etc. It's a pretty specific request and may take years to fill but if that's what you want then put forth the effort and go on a hunt.
If all else fails there are 79 Coupes all over and lots of people willing to paint.
Interestingly enough it was the 78 Coupe that got me into Cadillacs and I'm also on a hunt for another, but it has to be the right one. Extremely clean, extremely low miles.