Yep, I'd trust Heasemans - I believe Sydneykid (Gary Cook) worked with them in setting up the kits for Stageas, Skylines, and the Silvia/180SX/200SX ranges.
The SK kit now uses R32 GTR valving for the front, but the rear is stiffer than R33 due to the extra weight the Stagea carries.
It really depends on where you are and how far you want to travel. If you're out West, give Gary a call at Superior Suspension (they're in Minto), but if you're closer to the city, then Heasemans are the go.