So the spring in it now is a Ohlins 21040-29 90nm (there's another number on the packet that says SPRING 51/160/90). Like I said, it was not a straight swap, it did need collars, and there might be a spring out there that is a straight swap. (although you might be able to get away with putting it in without collars, but it would be a bit dodgy IMO)
The suspension guy recommended the stiffness of 90nm based on a rider weight without gear of 100kg (220lb). When you compare it to the stock stiffness of 80nm, I could probably have gotten away with a 95nm one too, but, I'm not planning on carrying a pillion ever so I guess it's not a biggie.
The only other thing I would say is consider having it revalved while you are at it. He quoted me AU$300 to do mine, and I passed for the moment figuring its easy enough to take off and do later if I think it needs it. He says he can take a lot of harshness out of small bumps with a revalve.