Grahamm, no doubt as the Marshall says, Hagons will have the answers, however, I think they would want a fair bit of info from you.
I would not know where to start, or given the answer,...... what RATE units it would be in?

I suppose they would want to know:
Weight of rider.
Weight of machine.
Unsprung weight.
Distribution of weight of from front to rear.
Angle of shock.
Length of swing arm.
Length of lower shock pivot point along swingarm.
Camber, castor and rake of front forks.
Service condition.... Racing, Touring etc.
A pretty tall order...... Good Luck!
RegardZ