I am thinking about lowering springs for the Peugeot but they aren't exactly cheap and plentiful in the states. Is there anything wrong with using some from another car if I can figure out the dimensions? I was thinking maybe a mkiii jetta would be close.
If the diameter on either end and the length is right, and the rate is close enough, I don't see why not. A spring is a spring.
Call ground control. I am betting they have done it before.
I found some info on a set of lowering springs for the 405, a little lower than I would go but it gives me a place to start:
Windings: 5,5
High: 320mm
Diameter: 147mm
Diameter wire: 12,5mm
So about 5.79" diameter and 12.6" or longer.
I'll have to try ground control as well, I didn't think of that.
Circle track suppliers have quite a selection of 5.5" diameter springs in many lengths and rates, might be an option for you.