SD, It's a roller furl into the main spar, as far as retro fitting, I don't know that you would want to retro fit, but designing into a new boat ??, maybe
Also, if I remember correctly, he had a little elec kicker on it too, though most of the time he just sail from the dock
One other thing I remember about this
rig was, When the wind was howling, this
rig didn't slap halyards, but it sounded like a ghost, kinda like blowing over the top of a coke bottle................really spooky