Hello, my wife is about 5'2' (her estimation) and about 115lbs. We had to replace the spring, which was only about $125 (it was a while ago, so my memory might be off a little, but it wasn't much). We also had Sargent make a seat for her (about 1.5" lower) and slid the forks up a bit. It was amazing the difference it made for her (but made me sad, because my much larger butt didn't work so well any more on her 599, hey, I have my own now, and it's a 919!!!!!).
Lindeman Suspension out of California measured and replaced the spring for us.
Good Luck, Steve