The Mk 2 jett carries about 25-30# less LF weight, at the same total. And the Cg is lower, farther to the rear. Pick up the rear hatch and you'll see why.
They can keep the rear tire lower in the air.
FWIW We built a Jett roundy car for the same reasons you suggest, more rear weight, easy body repair, better aero wise, smaller door opening(harder to get a car in there).
You need to get down to weight,I dont know what the lower limit is onthe MK 3
The MK 2 Jet, we have, weighs about 1920 without balast. But it is apples to Oranges , as my priorities were to get weight off of the nose. Lose the FI, PS, etc.
Did any MK 3 come without Power steering?? I have never seen one.
Good luck, Mike Ogren