I debated mentioning which hub I'm using because I'm wanting to ask a general question as well as figure out what to do in my particular situation. I'm thinking this would be safe enough because the rear wheel has taller flanges than the front (so spacing won't be way close) and the tension will be lower b/c the non-drive spokes (but I wouldn't build the wheel at lower tension than should be, because non-drive-spokes need all the tension they can legitimately have). I noted that Sheldon talks about building front wheels at slightly lower tension (which you can easily get away with) if you want radial lacing with a hub not rated for radial lacing. I cited that to imply that a well-built rear wheel with correct tension will have lower tension on the non-drive-side so half-radial will probably not endanger the flange.

Sheldon doesn't seem to have any worries about half-radial even with a rear hub not rated for radial, and even if that rear hub is used. I think he's right, from a theoretical angle, but wanted to get feedback specifically on that question. Sorry if it wasn't clear the first time around.

The wheel I'm building will be 128mm-spaced using a 7-speed freehub and 27" rim for use on my commuter bike. Hub is the 36-hole 105SC, gold-ish or puke-ish paint job, from the early/mid 1990's, used but in good shape and just overhauled. Road, will be well-built, used with 27x1.25" tires, although I ride plenty of roads that get eaten up by buses. Standard 3-cross lacing should be plenty strong on a 36-hole well-built wheel, but I'd like to try the half-radial lacing.