Post to Hardtop conversion

Not really an easy way to do this. As the above posters pointed out, the sedan roofs are taller. You can convert a 4 door sedan to a 2 door sedan without too much trouble, and it's been done quite a few times. Going to a hardtop would take quite a bit more work. You would need a donor car to take the roof and windshield posts from. You would have to use the tops of the hardtop quarters along with the roof assembly. Then you would need all of the hardtop specific weatherstrip, and a pair of hardtop doors since yours have frames around the glass. You would also need quarter windows and the regulator assemblies. On top of that I'm not sure the wheelbase is the same but I think it is.
An easier way to make the post 'disappear' would be to paint it and the doorglass frame and quarter glass frame flat black. Tint the windows a bit and the result looks pretty nice, I think.
Dallas