if you hadn't already, get some caster shims and a new steering dampener. after that i'd get a kamei air dam and possible a rear wing. Sway bars will definately help.
have you read the article on aircooled.net
http://aircooled.net/gnrlsite/resour...s/handling.htm
as far as handling goes at high speeds you're limited to the aerodynamic characteristics of the bug. changing this will give better handling.
Bigger better brakes will improve if fade occurs, but what sort of driving are we talking about at these speeds?