modified HT door on convertible?

The main difference is that the vert does not have the top metal frame above the glass. They also have different windows and the weatherstripping and trim at the back edge is different. Also on the later ones (88 or 89 up) the mirror is not in the window, but mounted on the door. If you can pull all the parts from the vert window and cut the top part of the frame off, I would think it should work. You might try installing a door with the top down to make sure it all lines up and then cut the frame off. Around here, coupe & hatch doors run from $40 up, verts you can find in our pick a part yards for around the same.

Good luck!