Sure I'd replied to this already........
Anyway we are looking at doing the same on our S23 this year....no ideas how we will go about it yet but have grabbed some inspiration from here CJR Vernon Site and will be doing something similar - Let me know how you get on and any costings please
Here you can find lots of ideas, http://www.atlantictowers.com/
I have ordered here a radar arch for my new boat,
With actual dollar currency very cheap !