Although there were no GT40s racing at this past weekend's Wine Country Classic at Sears Point (damn), there was one quasi-original GT40 in the Shelby Club paddock. It is quasi-original, because it was built on an original, un-numbered tub, using leftover spares purchased from John Wyer, back in about 1971. It lacks a proper P/XXXX serial number, yet it's built from original parts and has a known history from new. So it's in a no-man's land between original, and replica (or, as the less-respectful might deem them, "kit cars").
Anyway. His car was equipped from new with Vitaloni Sebring mirrors, mounted on top of the fenders (wings). These mirrors were
de rigeur for European prototype racing cars, Can Am cars, and exotic sports cars, in the 60s and 70s. They are available here:
Pegasus - Vitaloni Sebring Mach 1 Mirror - Convex Lens
or here:
Talbot & Co. aardvark international
(this is the home page; click on the "Vitaloni" link).
The nice thing about these mirrors, other than the fact that they look great mounted on the fenders, is that they are available with convex lenses, which will afford a wide, vista-view which can come in very handy when driving a tiny mid-engined car with restricted rearward visability.
Hunting around on the NVSAAC site, I think I found some photos of GT40s so-equipped. I am not particularly fond of the chrome look; most Can-Am cars (and Ferraris) wore them either in basic black, or body color, but I suppose the chrome finish would be more '60s-appropriate.
and etc. and so forth....
Note that Ferrari's solution was often to mount a single Vitaloni Sebring mirror on the roof!
Or alternately, on bloody great stalks on the front fenders/wings (this was common in Can-Am too).
Neither of these solutions is recommended for the GT40, however.
Most '70s Italian supercars used the Vitaloni Californian mirror, and although they look great on Ferrari Boxers, Panteras, etc., I don't know how well they would integrate with the GT40. Might be worth considering also. Unfortunately not available with convex lenses however.
FWIW....