I've seen some buses around that have a high roof.  Not a pop-top, but an
entire raised roof (about a foot and a half or so).

How can I install something like this on my hardtop '79?  Anybody got any
info on the conversion?  How does it affect gas mileage?  How much does it
cost (if I do it mostly myself) and who makes it?

TIA,

Cheese