If you are replacing spokes and nipples then there shouldn't be a problem as long as you get the right length spokes. The ocr rear rim will complicate calculations of the spoke length a little. Never done that with spocalc so I can't suggest anything there. However I will suggest two things on taking apart the old wheels - detension both sets of spokes before cutting. Also make sure you take the cassettes off first!

Chances are you'll need different length spokes anyways, so the reuse thing is fairly mute. If the spokes have some miles on them, best just to replace them. Also make sure you relace the old hub in the same pattern as it was previously.