circuit setup and drift setup are not that dissimilar than each other, wouldnt be able to tell u exact kg's
have a look at TRD spring rates i think u'll find there 8 front and 6 rear, and they were probably made for street and track.
also on another note, drifters started out using the stiff-est springs (and huge neg camber) they could, but eventually went softer (and less camber).