Ah yes, the spaghetti! While I'm still messing around getting the suspension and brakes worked out I sometimes stop to look at the roofline and tease myself with thoughts of chopping the roof so it looks as kool as Bob's.
Three or four inches would make a big difference to the frontal area especially if I didn't expand the roof and just curved the pillars in more. I think I would drive myself mad with the work involved, maybe I'll feel more like it when I've done all the tub work. None of the glass would fit if I did it, then I'd have to buy lots of Lexan and perspex. Then I'd have to bend it all to make it fit the curved shape of the car and make window frames for the doors. The glass is already almost a flush fit so the aero advantage of perfectly flush Lexan would be minimal. Then I'd have trouble seeing out of it and my brother is as tall as you so he wouldn't fit unless he sat on the floor.
And worst of all, the time and effort would guarantee I'd be a no-show for 2009 so I'm on a hiding to nothing if I commit to it. Plus I was relying on the glass breaking if I ever rolled it so I had more escape options. So the final decision will be made when I have the engine in and the car has finished suspension and brakes. Then and only then, I'll start on the cage.
Good, Fast, Cheap, pick any two!