I have seen a new longboard with windsurf capabilities, i.e. mast connection slot box.
What sort of sail would you use on these, a fully batten one or one of the old non batten styled ones out of the early years of windsurfing?
Does anyone actualy sail their longboard here in Perth?

I would say no, I haven't even seen anyone sail their SUP's that have sailboard attachment points, even guy's that have heaps of sails and rigs.
I do remember about twenty years ago there used to be a guy and his wife that would wavesail on old gun surfboards, usually around the Watermans area. Had Farrelly sails I think. What ever happened to them?
There are any amount of old windsurfers about going for basically free, better off on one of these and get a proper longboard for surfing.

I saw a guy a couple of months ago on a Naish 11.6 sup, the first half hour he used his paddle sup'ing them attached a sail for some time then prone surfed the beast.

He had a ball all three elements in one outing

The reason I ask is that I just picked up the Starboard catalogue and at page 35 there is a page with the 9'0" x 33" Hero and a description and poto of it being sailed by Bjorn Dunkerbeck!
Sail Severde code red?
and a big sail at that!

This sounds like a SUP longboard not a regular surfing longboard. Your could play around on it but not seriously paddle and surf a 33" wide surfboard.

in the same catalogue there is a slightly smaller SUP? on page 31 which has an almost complete non batten sail in the picture ripping through the surf.
And the K15 race board also has a mention in it's description of being able to windsurf.
(Beautifull produced catalogue by the way.)
In the back of said catalogue, where all sorts of nice add ons for the SUP's etc. are illustrated, there is sadly no further mention of the windsurf option and avalability of it.