Well I put in the Empire axle, and at least at 30mph it's silent so far. I'll take it on a Bay Area commute tomorrow, so should be able to get it up to 35, 40mph if lucky & will report back once I get it up to speed.
As an aside, the ball joint came out of the knuckle easily for me--just a little rust on it (California, right?). But I had a bear of a time getting the axle out of the hub. Ended up using a puller, hammering and using a breaking bar on that, and oh-so-gradually it started to budge; from there I just hammered it out. I think I whaled on the puller so hard I screwed up its threads. There was a lot of oily, black, grainy crud on the splines. Greased the new one of course.
Thanks again for all the advice.