Is this the boat? http://tallahassee.craigslist.org/boa/2497954317.html
If so, then the rudders that are shown don't belong to it. The 3.5 had wooden rudders.
At 170 lbs, you would be far too heavy for it. It was really made for kids. Here's a link to a page with more info: http://www.thebeachcats.com/pictures/?g2_itemId=61801
You're better off finding a Hobie 14 or Hobie 16. Both can be found inexpensively and parts are plentiful.
Still looks like a neat little boat. I really like the 'double stack' with an H14 underneath... or just throw it on the roof rack!
The sail has 5 battens like an H14- I wonder how much it would take to modify an H14 sail to fit? Maybe someone already added H14 rudders- or else it could be easily done... But then there is the dreaded 'hull rot' situation
If I lived closer I'd pick it up for the grandkids- and as a 'Hobie Heirloom'. Wonder what shipping from FL would cost?