The easy answer would be that CB750, CB500, CB550 and even the CB450 should be the same or an easily adaptable alternative (the renowned dohc parallel twin CB450 that is...likely the CL450 too)
If you're interested in adapting modern alloy wheels, check the link in my signature line. I have compiled a good list of resources for such swaps. A few of the parameters you'll need to be aware of are: tire size and it's relation to wheel size, axle and wheel bearing sizes, how to approach finding the right sprocket and how to achieve correct chain line, as well as what you'll do for brakes! it cal all be done with modern components and if you choose carefully you can do it with a minnimum of custom pieces. Cost can be considerable, but again if one chooses wisely costs can be held low.
Swapping out the forks as well as the front wheel will eliminate quite a bit of re-engineering as far as braking systems go.
Cheers and good luck, PM me with questions if you like.
-Alan