Do I need to prepare old pipe to install a compression fitting?
Generally speaking, the ring compression should work just fine. They don't look it, but they were standard long before the push-fittings came along and made this stupid easy. As long as there's nothing under the ring, it should seal properly.

I would get a wheel-type cutter to do this, however. Not only will it not burr the pipe, but it won't bend it either.