Z1OwnersClub GB

Hi, i have a Z1B which rides nicely except the front forks seem a bit too hard, despite stripping and cleaning the forks but no better.
The springs fitted appear to be progressive as they have tighter coils at one end but they are about 510mm in length.
I did buy a set of new Hagon springs which stated on the box "fits Z1, Z1000" which did alert me as they use different lengths for these models.
I fitted them but they were too long and the forks could hardly move, so put the old ones back in and got a refund.
Has anyone found springs which are the correct length and spring rate for this model, 495 mm is around the length they should be., the Hagons were over 520mm.
Progressive rate springs are rated as a good improvement but finding the right ones is tricky.
Any help or advice would be appreciated, i have searched the forum but no joy so far.
Thanks

What weight oil are you using?

I use 10 weight but have tried 5 but not an oil issue.
it is the spring tension/length that is the problem, that is why i asked here on the forum if anyone else has any idea as to where i can get springs suitable for the Z1B.
As i said i tried the Hagon ones as they were marketed as for that model but were way off the mark which surprised me as i thought Hagon knew what they were doing.