has anyone ever considered mounting a spitfire or gt6 body onto the chassis of a tracker or sidekick? i recently saw one on a jeep and it got me thinking that it would be easier to use a smaller 4X4 frame.

Um, not me.
Little enough head-room on smooth surfaces.
Keeping the bonnet secured might be an issue too.
And getting into it if it's been raised to clear larger tires might be amusing to watch.

Did see a Bugeye Sprite done on a CJ5 once, looked like it was probably a pavement queen.
Even the magazine I saw it in only took it to some gentle dunes for the "Off-Road" pics.

An old Hillman traveller, convertible, or EnFo Thames van might be interesting.
A Hillman might not be too hard to find.

I have a Suzuki Samurai that I use running around the place, it has a narrower track that the Tracker. The wheelbase may be about right. Ride height will be greatly increased of course but it depends on your intended usage. I expect the engine will stick through the hood.

Jim