Thanks much for all the links, had already seen a few (but reread those), LOTS of good info and plenty to consider.
A couple of things I came across: a few posts state that the CB350K and CB450K both use 17mm axles, this is not correct, the CB450 is 20 mm (as is the CB750)
A few others said that widening the swingarm slots to accommodate a 20 mm axle would weaken it excessively, but OTOH there have been several references here to CB750 wheels being used successfully so I'm not sure what to think on this...it LOOKS to me like taking 3mm off the top and bottom would be OK but of course that means very little.
I'll have to decide whether to proceed with my CB450 wheel or find something else w/ a 17mm axle...in its favor the CB450 wheel appears to have the sprocket in the right position relative to the rim center and that is a BIG plus.