Those are the kind I use.
Zip tie the spokes, I've got thousands of miles, none bent, none loose, and we inspected the bearings a few months ago. Perfect condition.
Put about 4 layers of tape (I use electric tape) over the spoke ends, put in a puncture-proof tube ($8) and you'll never have to worry about adding air.
Sorry read the wrong post, so your positive these will work? Not questioning your knowledge just don't want to but stuck with some useless rims. But it'l work for a 21 speed mountain bike? Also, what did you mean by zip-tieing the spokes?