Recognizing that the stock rear shock is not optimum, what would you recommend as far as settings on the stock shock for a 90kg rider? What would be the sag recommendations? Also, what weight shock spring would be appropriate for my weight and where can it be purchased? I've seen multiple cautions about having the correct size spring so will want to ensure I buy a spring that will fit. I've changed out the fork springs and shock spring on my Beta and KTM dirt bikes so have some familiarity with that job.
Ignore all this. I wrote it when I was tired (I know what rider sag should be) and before I spent a few more days reading all the posts I could find on suspension matters. I understand that changing the spring on a stock GRiSO shock will still result in a sub-optimal solution so my first suspension upgrade (other than using the Ghezzi method to improve the stock setup) will be to buy a new or used Stelvio shock or a Hagon shock built to Stelvio specs (thanks to Sidrat sharing that info).