I make my own gaskets from a rubbery type paper gasket material I get from Auto Zone, they sell 2 kinds, a thin paper for coolant only, and the rubbery type ment for gas & oil. After tracing out the clutch cover & cutting it out, I ended up with a peice that was almost a perfect match to fit inside the cover. Because the cover is already raised be the gasket, I figured it would grant me sufficient clearance inside & not rub the "sound deadener" slice against the flower nut. Just coat the inside with RTV and place the gasket slice into it, smoothing out any lumps with my fingertip.
Another tip if you hear gnashing gears: crayons. My dad taught me this trick as a kid, use crayons on the chain & sprocket. The friction from the moving parts heats up the wax to penetrate the pores of the metal and lube the chain. It isn't messy, won't attract dirt, won't sling off & stain your pants leg (if your bike lacks a chain guard), and helps quiet noise. I also lube the gears inside my clutch cover with crayon and it works great! It made the gear noise almost non existant, you have to remove the cover to hear the gears now. Another benefit, the waxy coating deters rust & corosion. Any brand or color works, but I like to use pale blue when I color the teeth of my chrome sprocket, it doesn't showup as much.