Hi Tony209 and others!
I hope that everything ended up good with spring replacement.
At the moment I am at the same situation and I am still wondering what springs do I have to install at rear for the best possible performance. Basing on your posts looks like 430mm (Sachs) is much better than KYB/Lesjofors 400mm springs.
I will not replace the rear shocks, just springs.
Could you tell me how the replacement ended up, please?
I would appreciate if you could share picture with new springs installed at rear end.
Thanks!