If you fit shocks and springs from a Mk2 onto your Mk3 then there might be about 10mm difference because the Mk2's have a different spring rate so are set up for a lighter car, the Mk3 is a heavy car so the springs might not hold the car so well if you get me? Therefore, sitting a little lower than they would on a Mk2..
For example, I fitted 40mm Mk2 lowering springs to my mates Mk3 and measured it afterwards and it had dropped 50mm.