I have a Brass Button clutch at the moment and im thinking of going to a Cushion Button Clutch for more everyday drivabilty and less stress on the gearbox.

What do you guys think about this clutch, will be running excess of 330kw atw

A genuine 330kw at the wheels, you'll be struggling to keep it together with a single plate.

Check out the Exedy twin plate clutches...they are fairly nice to drive and will hold the power your chasing, not to mention they are more forgiving on the gearbox than a button clutch!