I'd also go with CVT upgrades next. I'm a fan of the Malossi variator knockoffs like the Hoca from Parts For Scooters . About $50 and improves acceleration and speed in my experience. You'll need to tune it most likely, so don't expect the rollers that come with it to be just right for you. I'd buy a tuning kit of 16x13 rollers or just pick up a few sets. If you haven't done clutch springs yet, you might wanna get a set to install while you're in there.
With respect to the gaskets. I'm not sure which base gasket I used. I got the squish to 0.90mm. (rec amt from instructions). I did not use a head gasket. With the thinnest one I could not get the recommended squish. I used high temp gasket maker. ( just a touch) -C