Have you checked to see what's already on it? The spring & damper codes are on a label under the back seat.
According to the chart (bottom of
this page), it should have left the factory with one of these:
ZT & ZT-T Standard (Early Models): GB - RPD000150
ZT & ZT-T Standard (Comfort): GC - RPD000151
ZT & ZT-T Sports: GD - RPD000530
Don't quote me but I'd say the Comfort GC code (RPD000151) is fairly similar to the 75's G code (RPD102250). I've got a 75 saloon and it's pretty solid at the back.