Good news for anyone who got one because they thought it would be collectible.
jmedia -- Unfortunately, plan taper in the cabin is not going to be a bolt-on for your '89 Escort. However, it is an opportunity for me to point to one of my favorite roof-lines, the VW Golf GTI w-12 650:
In case you can't see it in the picture, it puts what's called a bubble-top coupe roof inside the hatchback roof-line. It has plan taper, and the back of the top forms a wing.