Mechta,
I flew and was involved in training on SD330/360 for many years, and the fuselage was never mentioned as contributing to lift, or affecting the stall in any way.
It did collect a lot of ice, and the drag (on SD330) was sufficient to have you lean forward in your shoulder straps when the power was pulled off!
The people in Shorts now Bombardier were very helpful, and maybe they might be able to answer the question. Good luck with the project.
Emoclew