Don't know about paddocks, but here are the heights for the britpart ones..
FRONTS
* Type 4201 1†(25mm)lift with 25kg load-200lbs/in
* Type 4202 1.5†(38mm) lift with 50 kg load -230 lbs/in
REARS
* Type 4203 1.5†(38mm) lift with light load -220 lbs/in
* Type 4204 2†(51mm) lift with 100kg load - 300-340 lbs/in
* Type 4205 2†(51mm) lift with 200kg load - 360 lbs/in
I'm using 4202's on the front of mine. The Britpart springs have a good reputation.
Cheers
Steve