Mate, if was were living here and wanted to windsurf, you'd be doing longboards too. And ice hockey in the winter.

Back to the question: if his model is 1985 indeed (how does he know, did they really have the years on the board??), then this is not the mast T nor the dagger that was being used then.
The mast insert for those models was a full slider, with a little pedal. I'm pretty sure it's the case of the Aussie-made version too. Mind you, there was a year (1984??) that had a slider and a hard plastic receptor for a black mast T bit.
Ditto the centerboard: the 1985+ vintages were already on retractable daggerboad.
Will wait for more details from him before looking for answers.