EJC, i have only ever cut Carlisle oars as they are just aluminum wrapped in plastic. I currently own Cataract oars and would break out into a sweat thinking about cutting them.
I would email Cataract (if you haven't already) and see what they recommend. Another forum that has a ton of rafters on it is "Mountainbuzz". Folks on there are really knowledgable and happy to share info. I imagine you're not the first person to do it......