The 250 lb springs up front, and 27 mm Torsion bar in back would make a good street/track combination. You want to keep a balance with the front and back spring rates. Going stiffer in the front (300 lb) will induce a little more under-steer, which you may, or may not want.
A 30 mm Torsion bar in back should be balanced with 400-450 lb springs up front. This is our current race setup, and is probably too stiff for regular street use.
YMMV
good luck
JM
