The Campy cranks you have are 1978 (diamond 8) and 1983 (circle 3). I checked Sutherland's, and the Campy standard road spindle changed width (for English BB) from 112 pre-78 to 114.5 after that. Theoretically, both cranks should fit a spindle the same way, but manufacturing tolerance and wear may be the difference in what you see. The late spindle had a shell (to) end, right (SER) dimension of 25 mm, while the Sugino Mighty MW-68 spindle has SER = 27, even though the spindle itself is half a mm shorter than the Campy. If you only have SER = 22 mm, that's clearly not in the ballpark. Either your spindle's shorter than it should be, or your cups are sucking up too much right spindle!

Are you sure that you've got the long end of the spindle on the right side? Both Campy and Sugino spindles are asymmetrical. With a Sugino, it will make a big difference, because the right side is 6 mm longer than the left (Campy's only 3 mm different).

In any event, if a shim will fix it, you should be OK. Just be sure that you have enough chainwheel clearance so that when you're standing/hammering on the cranks, they don't flex into the stays.