hi guys,
how do you trace the suspension load paths & which material you are using for uprights according to the strength

A very good method of construction is forming the uprights out of sheet chromoly. I won't get into specifics, since you guys will have to do your own engineering, but it offers an excellent stiffness and strength to weight ratio versus machined aluminum. Mclaren F1 cars used this method for a while, and I see them on American Lemans Prototypes also. TIG welding is a must for this type. Hope this helps.