I'll also note, there's an annual
wooden boat festival in Washington state, which would be an excellent place to start making contacts. There are also books on building wooden boats; I haven't checked them out personally, but I've seen them available through Amazon, etc.
I'd also second the suggestion of starting with a model. If money, tools, time, and workspace are all not issues, try a large scale of about 1:4 (1' on the model to every 4' actual). It's a large enough scale that pretty much every detail can be included, and furthermore the wood will behave similarly (so I am told!) to the way it behaves at full scale. Valid nautical archaeology experiments have been carried out at this scale, and taught us much about building period ships. Plus, since the model can be fully detailed, it should teach one almost everything there is to know about the plans from which one works.
Lastly, plans from the National Maritime Museum in London don't cost nearly $4000 -- the reproduction fees are closer to $30. I believe the Smithsonian Institution has a collection of American boat and ship plans, but if memory serves they're all post-Revolutionary.
Good luck to your father!