I've been searching for (and worrying a bit) about how to get stability data, a plan drawing, and various other bits for my steel Van De Stadt Vita 30. I purchased "Pandorak" (you can see her story here www.pandorak.net) as salvage. I wasn't looking for a boat at the time, but when I heard that this one was going for scrap, my heart sank. I couldn't let "the yellow boat" die.
Luckily, Van De Stadt is still in full swing designing yachts. Cees van Tongeren had previously sent me sail plan drawings absolutely free of charge. I found that for a measly 15 Euros (about $16.50 USD, the price of a lunch) I could have the study plans. They include very nice figures for stability, plenty of diagrams, and a great deal of information I don't need at the moment, but will be useful later.
A good naval architect could replicate all of this data with enough sweat, but I'm sure it would cost more than a lunch!
For those doing conversions, the moral of this parable is this: If there's any chance of getting the original data for a hull, it certainly doesn't hurt to ask. Most designers are somewhat romantic, or they'd be accountants. While some may view the junk rig as anathema, they'd rather see a sailing junk than a scrapped hull.