I am having difficulty with the conceptualization of the steering mechanism and how it will 'talk' to the rudder box. Any input, especially photos of finished boats would be invaluable. I want to use a wheel and avoid a tiller if possible. I trust that the members will have numerous solutions to our common problem...... ???
thanks to all who reply,
Sean
Use a tiller
The wheel steering is at best an unnecessary contrivance in a boat of this scale. As designed, it has less then notable tactual feed back from the rudder, a fair bit of sloppiness, maintenance issues and a host of "usual complaints", easily found in the archives of this and other discussion forums. The first thing you should ask yourself is "do I really want a wheel" or better, "what's wrong with a tiller?" If you have sailing experience, then you know how important feed back from the helm can be in some situations, like avoiding a broach. A tiller is unmatched in this regard and unquestionably the choice of 99.9% of designers world wide, in sailboats of this this general scale. The wheel is cute and does function, once you play with it and work out the kinks, but that's all of the good you'll get from it. It's heavier, much more complicated to build, tune and keep working, compared to a tiller. You may be able to tell I'm not particularly fond of this wheel arrangement, but hundreds have been built.
It might be best to ask those that have changed from a wheel to a tiller, why they did and what they think of the results.
Paul says it so much nicer
 My tiller comes into the cockpit only a few inches further then the wheel arrangement take up. It also can hinge up completely out of the way or when standing to look overt he bow.
I just sailed with Warren Percell on his great boat...and he did switch from a steering wheel to a tiller...if he does not chime in then send him a PM...
My Weekender has the wheel.
I took a long time to draw, cut and finsh the wheel. Then I wasted time for assembling, gears set-up and trim, modifications from original design (everyone has his personal idea about).
The result is a heavier and not intuitive system that dramaticaly reduces available space between lazarete and transom and force to open a window in the transom.
In spite of all these things, I think that you decided to build a Weekender because you've been fascinated by her old style look and the wheel contributes greatly to it. With the same money, we could buy an unpersonal and commercial used sailboat, but with better water performances and immediately ready to sail.
Home building is not decided to save money, but because for us it is pleasure, the same for the choice of building a Weekender.
My advice is therefore to build her with the wheel, get compliments from all your friends and all home-water locals, then when nobody care to her anymore switch to tiller if you like it. It will be your next winter season occupation.
Gianluigi
There are probably as many different ways to set up the wheel steering as there are builders. As designed by the Stevensons, the system works pretty well other than the ends of U bolts sticking out the rub rails of the boat.
Here's some pictures from my build and others to give you some ideas.
One thing I will strongly suggest is that you get the steering mechanism sorted out before you put the sides on and also consider some sort of hatch(es) on the aft deck so you can get to the mechanism later.
Good clear photos of the setup Andrew.
I did the wheel. I never had any trouble until recently, careless powerboaters whipping by my dock made waves that damaged my boat, and I had to take the wheel out to fix the bearing. Then when I rigged the wheel again, I accidentally rigged it backwards and didn't realise it until I went sailing in a strong wind. Oops...
The wheel is pretty neat, but if I was to do it again, I'd probably go with a tiller. There are times when I'm sailing by myself that I'd like to hike a little more than I can now, but I can't because I need to be able to keep a hand on the wheel. Also, I would like to be able to sit further forward when I'm the only person in the boat. I feel it sails better with the centre of gravity farther forward than it is with me sitting right in the back. A short-ish tiller that hinges up and has a removeable extension for hiking in high wind while sailing solo would be pretty handy. I would be able to sail better if I could reach the helm from more positions in the cockpit.
My wheel is pretty smooth-turning though, I get some feedback from the rudder. It's good enough that I'm not going to bother converting to a tiller, at least not unless I need to do some serious steering system repairs, then  might think about it.
I've steered Keith's boat with his wheel, it works fine, but as he says, nice to be able to get your self into other positions in the cockpit.