I know it's an old post, but if you want a plate/clutch, Kaaz do 020 and 02J centres at pretty reasonable prices for an extremely well built unit - sub $1500 landed. In regards to plate vs ATB/helical, I am a big fan of the Quaife and Wavetrac units. The traction increase is very noticeable and they are very well mannered for parking etc. Unless you're lifting driven wheels all the time in an extreme track machine I reckon the helical style options are all good!

And MFactory do indeed seem to have plate options for the 02M 6-speed as of 2014.