I fitted 1kg/mm springs, Racetech gold valves, & 15wt oil years ago. Fantastic improvement. I also fitted a Wilbers rear shock. Others who ride newer bikes are surprised how well it handles considering it's age and weight. You won't be disappointed and I haven't heard of anyone who has done the upgrade going back to stock.
I have pushed my forks 6mm through the triple clamps to improve steering responce but I don't think it has made much of a difference.
A fork brace can help improve handling especially if the bike is a '94 or younger model.
Regards, Russell