Tri-spokes etc

oh todd, that's a shame! Is it tub or clincher, your rim? I'm surprised that they don't have replacable hubs. Tekk a hacksaw to it? Shrug...

Is the width of the cassette part more than 100 mil?

Yes it's a shame. But like I said, it's spare so if anyone's interested in trying to convert it, I'll sell it. It's for tubs. I bought a (reasonably priced) pair! ;-)