for a weight of 11 1/2 stone i'd consider going even lower than an 80 if its for the track. I'm 12 1/2 stone and have an 80 on a TTX. It might be because I have junked about 40-50 lbs off the bike; but I still sit on it and it sinks only a few mill (about 5-6...)
Junking 40-50lbs equates to nearly 3-4 stone! I was very happy with the spring in my 749, and was getting the full range of movement. I won't be doing many track days as I'm getting a bit long in the tooth, but do like to ride the bike how it was designed to perform.
