Hello Grandpa,
The grp hull is almost certainly a 'Cheverton Crusader' class yacht designed by David Cheverton.
If you want to see many photos and a set of lines, go to the Cheverton website. (Google search)
I have sailed on one owned by a good friend, a lovely yacht that really sails well. if you decide not to proceed with the model, let me know as I think he should make a model of 'Pentoma' as a winter project!
All the bast, Lemmerhengst.

A Bermudan rig or a twin foresail design would suit that hull .http://www.cruisingworld.com/double-your-downwind-fun-two-jibs

Hi Grandpa

Sorry I took so long to respond, I was doing some work on my Server anyway.

No I don't actually have a link, What I did was just do a Google search for model Sloop plans.
looked around for something similar to the hull design you have.

This is what I searched for "friendship sloop model plans"

I uploaded a picture to help you see what you can make with the hull.
hope this helps

Ed

Also I just saw a Sloop design that I believe is better suited to your hull design.
Unfortunately it's a small picture, so the details are a bit hard to see!
Again it's just an idea.

Ed

Hi Grandpa

Here's an idea maybe you can make a model of a Ketch, it's only an idea
If you google a ketch you'll see plenty of designs, she has lines resembling a ketch.
Remember it's just an idea!

Ed