I've just got hold of an American Classic CR350 rim and also their Ultra light rear hub,I want to build up a light a wheel as possible and wonder if it's safe to build the non driveside radial?I wanted to use CX-Ray spokes,but maybe I need a heavier gauge to build radial? [snip]
A lot of wheels use radial NDS lacing, and 2x or 3x on the DS. It would depend on your weight, riding style, rim dish, and hub flange strength...the 350 rim can take it, but I'm not sure the AC rear hub is designed for that. You should ask AC or a really good builder. Dave Thomas used to use AC hubs (now uses White) and still uses CX-Ray, maybe he can tell you, or contact Joe Young.
I weigh 185# and my SpeedDream AeroLite with CX-Rays, are completely fine.