You may be right. I don't think they were 2800 lbs, but I got my information more or less from the Horsman book, and a lot of his info about GT40s is about the Wyer team cars which all had small-block engines and ZF transaxles, which are lighter than T44s and 427s. Maybe 2300lbs; they had early CF body parts and some aluminum as well. The GT40 was heavy for a race car, I do know that. The Mirages that the Gulf teams fielded soon after were much lighter cars.
Urs' car is going to be very light indeed. So light that you think about ways to cut weight out of components that you don't usually think of as heavy- the glass windscreen, for one. It sort of sets you off on a chase to take weight out of everything. It will be interesting to see what kind of spring rates he picks, etc, because when you make the car so much lighter all those loads are different and I would assume less. Lighter springs, lighter shocks, different sway bars- the list goes on and on. And the fuel tanks become a proportionately bigger part of the car and affect trim more as the fuel gets burned and the weight distribution changes....it's all very interesting.
I love the carbon fiber control arms. I wonder what one of those would cost....