Zook,
From what I beleive, the Hawk rim/hub uses a four lug bolt pattern to attache the rim to the hub. The NSR (as well as VFR/RVF 400) use a single axle, with a large lug nut to attach the rim to the hub. I have seen people swap the VFR750 rim onto the hawks with little trouble, but I would guess you would need to swap out the hub on the NSR to match it up to the Hawk/VFR750 rim.
I know from working on the NC30 that I owned, as well as the NC30 my girlfreind owened, and the 748 that my girl friend owns, the axle on the duc 748 seems to be a little more beefier then the NC30. Since the NC30 hub is basically the same as the NSR (swaps out) I would suspect the 748 rim may not work on the NSR.
However... It may be doable to swap out the NSR swing arm with a 748 swing arm, and then you can use the duc rim.
I guess you could also look into a pre-2001 Honda RS 250 rim, turned backwards (as the drive line is on the right on the RS), and go that way. You would want to check the RS to see if it's got the same axle diameter, and offset as the NSR (that I don't know).
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Charles Gallant