Like Bill V said, there's not much weight to be lost on the flywheel by going with a whole (no material removed from the circular shape) lightweight one. The original flywheel is already relatively light compared to later model 'wheels. The type that Kurt posted is the next step. Obviously any amount of rotating mass is going to make a difference. It's just that there's more savings to be had by going with a lightweight pressure plate/clutch housing. It's good to know that the alum. housings have had some problems. Add that to the brain bank.
Anybody tried Spec clutch kits? They seem to have a pretty good following with other makes, like BMW.
http://www.specclutch.com/specMain.html