I take it you don't want to stick the drivetrain into a '95+ body? Yeah, they're a bit heavier, and not in your current collection, but the starting aero is superior.
Also - that chopped EV Metro dragster looks hott:
Another crazy aero-modded Metro - chopped & teardropped
Narrowing the entire car would be good, but man, that's a LOT of work.
I think the biggest bang for the effort is definitely the firewall chop / roof tilt back. You'd be dramatically improving Cd, as well as slightly reducing A (the projected max height of the windshield would be lessened).
Retaining the OEM windshield would seem a key goal also for safety & non-scratchiness (wipers on lexan).
So that would get you your profile taper.
After that, if you want to get seriously cutty & weldy, I'd look into doing some plan taper via rear track surgery and boat-tailing the body after the doors. As for handling - you don't have to make it into a
trike exactly. (The rear track on my '98 is already an inch narrower than the front, stock. Maybe it's only half an inch... I forget at the moment.) But 4-6 inches narrower would be nice.
Radical aeromods are definitely the way forward for you, since like basjoos, you don't hold back too much in terms of cruising speed.