I decided to go with a double chain but for me I had a high horsepower application. However, even if I hadn't I probably would have done a double chain because they last longer and over time they will keep the cam in more strict alignment as a single would stretch more (stretch would probably be pretty negligible). I should point out that timing chains do eventually wear out and while you have it appart it would be a good time to do it, unless you plan on pulling the motor again in the future.
For me the timing chain is a safety part. It may never break or it could eventually fail. That would kill the engine. I would recommend you replace it regardless.
However, XFire82 is correct. If you didn't pull the whole motor replacing that crank gear could be a more of a hassle to you then it's worth and in that case stay with a single.