you cant get 70mm lowering springs for saxo (althoguh im sure someone will say you can)
and if you going to go down 60mm at the front, you want some better shocks too, even some buget ones are okay like apex or spax vsx.
im -60 at the front on just springs and its fucking horrible
the rears are not as essential as the fronts so if your just going for the look, just lower the torsion bar to match the front.
although on saxp people will tell you that you need the most expensive suspension all round. but just get what works best with-in your buget.
hope this helps