The 84-85 T-type turbo Riviera and the 84-85 hot-air Regals use the same intake manifold and heads. That intake will definitely work with 86-87 3.8 front wheel drive heads, (Mine are 87) and some other years as well. Most of the heads from 3.8 front wheel drives will probably work, but I can't guarantee that to be correct. You definitely CANNOT use the heads from a 3800. The 3800 is an on-center block. The 3.8 is not, so the heads and intakes from 3.8s and 3800s are not interchangeable. While you could use front wheel drive heads, it does create other problems. If you use the front wheel drive heads, you will need to custom make your own headers or exhaust manifolds, or modify some front wheel drive ones to fit. Neither the manifolds from the Riv or the Regal will fit properly with the front wheel drive heads. This I am sure of, I did alot of experimentation before finally going with the set-up I have in my car. Also, the bolt holes in the ends of the heads most likely are not going to line up properly where they should for your accessory brackets - alternator, etc. I used front wheel drive heads in my car because it helped solve some issues. (all of my accessories are from front wheel drive cars) If you have the space in your jeep to use the complete regal set-up, in its original configuration, It would probably be your best bet to stick with the original Riviera/Regal heads, regal exhaust manifolds, turbo., etc. While I do think that the front wheel drive heads do flow a little better than the regal heads, A good set of ported regal heads would definitely outflow the stock front wheel drive heads. There is a certain amount of fabrication involved to use the front wheel drive heads, so if you were considering doing it strictly from a performance gain standpoint, you would probably be better off sticking with the original heads and just porting them. Like I said, using the front wheel drive heads helped me solve some other issues, which you probably don't have in your application. In your jeep, going with the original stuff will be alot easier ( if it fits ).
I hope that helps you some, if I can help you anymore just let me know.
Good Luck!
P.S. I really would like to buy that Riv turbo from you, but right now I am just to darned broke. If you still have it around the 2nd week of January, I'll take it then.
Also, feel free to message me if you have any specific questions I may be able to answer.