Put the year of your bike up mate and I'll check the spring rate for it - will be able to let you know how close it is.
In general though the FZ1 shock isn't particularly good from what I've experienced, for my (10 and a bit stone weight) it was relatively seriously oversprung and also underdamped, best (but most expensive) bet budget allowing is to buy a decent aftermarket shock for it. My personal vote would be one of the Nitron range