What did you end up deciding to do? lots of nice options out there. I like the idea of making an aluminum spacer that's super easy to fabricate. (you know a guy LOL) Perhaps wrap the alum vs paint. If you make a spacer with fiberglass and foam that would work well. It was pretty difficult to get the fitment right and I got it about 90% good enough and decided to accept some imperfections. 4" of roof raise seems about right, more is really nice your tall friends would thank you, but you start to change the roof lines and then it doesn't look as nice in my opinion. If you are re-using the old windows as I did, take caution as you raise the roof the windows go further back so my new spacers at the aft of the windows became pretty small. End of the day they are still sedan style and really designed to be run sitting down.