The frame ties will stiffen the car quite a bit, but a 6 point bar would add a great deal of stiffness to the car and prevent flexing. As far as intakes, I alway go with the bottom end torque v the high rpm horsepower. Bottom end torque is much more usable on the street. A Detroit Locker is the best drag race set up, for street use I tend to favor a posi type unit instead---The Auburn is a good unit on the street.

I would defer the cylinder head and porting questions to Mr. Kane !!!!!