[axsaxoman]

unless you are using a lug drive alloy type racing clutch ,then the weight of your clutch cover + plate will be as much as the flywheel --so lightening it makes very little dif on anything other than a full race engine --
weigh them ,then see where on the dia you can remove the weight --mostly in the middle, so removing weight in the middle has far less effect than removing weight at the outside of any rotating object ..
do the maths -- 1lb weight at a radius of 1ft =1lbft .to get same reuction at 6" you must take off twice the weight .
no doubt you will be using big wheels +tyres --they also act like flywheels ,so you can take far more wight off them by using light weight rims ,also makes suspension work better --less"unsprung weight".
you can save 20kgs by buying mag rims ,whole flywheel only weighs about 5.5kgs