Holy smoke! This would be interesting to see it done.
There are some really creative minds in the 1979-1995 general talk subforum. Post this question along with some pictures of any progress you've made toward that end.
If you're serious about tackling something of this magnitude, I'll bet you'll find quite a bit of help from the guys there.
As I'm sure you're aware, this idea is so much more than just "sticking the engine in the back".
@madmike1157 will be of particular help. He's an incredible fabricator. I think he'll want you to prove you're serious though (hence the pictures).
Welcome to Stangnet brother, good luck, I very much hope you can do this, it ought to be a very fascinating process as well as an end product.
Just reread your post, I saw "'89" and I automatically thought a fox body! What is an '89 dignify? Wait on posting in another thread. My initial advice may be incorrect.