I have the older RS forks, 41mm conventional. I just slipped in a pair of VTR1000 springs. I dont remember the spring rates off hand, but the VTR rates were right in the ballpark of what I needed, and a bit stiffer than the RS springs that came out. These springs will also work in the NSR stock forks, but you will need a custom length spacer (aka PVC pipe).

With all the diesels out there that switch to stiffer springs and toss their stock ones, I bet you could come up with an easy swap into the inverted RS forks.

That is one reason the NC35 forks work so great. With stock springs, they are set up stiffer than the NSR forks.
_________________
Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
MY BIKE PICS