recently i got some new sugino 75 cranks to replace my gipiemme strada cranks. when i put the suginos on the campy bb i noticed that they don't sit as close the the bb shell as the gipiemmes. is this because they have a different taper? and is this going to change the chain line?
Campy BB and JIS taper (sugino) do not mix! Take em off! You might mess up the tapers. You want to get the correct BB for the Suginos - they of course have a matching one though I'm running a Shimano 107 with mine which works fine.
prolonged use will definitely damage your cranks (steel spindle into poorly fitting aluminum cranks = messy!) Any shimano/tange bottom bracket should have the correct taper (provided it's not *gasp* ISIS spined.)
just to make few things clear, their taper angles are same, 2 degrees. but jis are slightly bigger than iso, so usually when you put jis taper cranks on iso taper BB, they sit further in, sometimes bottoming out. from your description, your gipiemme cranks are worn, and maybe bottomed out, so check that as well when you install them.