The roof we rebuilt had torsion springs inside the tubes that run along the length of the roof. They load when the roof is lowered, and unload when it is raised again. That would throw off your calculations.
That is also the reason why the rear corners of the older roofs tend to soften and give way. They have to bear the torque of the loaded spring when the roof is down.
Also the scissor mechanism should better only be removed when the springs are unloaded...
I don't know if my Outfitter had the springs or not, but I had the electric lift and did not really care.