15 Bing will be fine.
Stock pipe isn't going to allow you to hit the RPM's that you will with an expansion chamber, but then again I don't expect that you'll be blasting it at first anyway.
Some people say break it in exactly how it'll be ridden. I say just try it, ride it at no more than 75% of throttle for like 50 miles, give it short random bursts of WOT. When the ring seats, the ring seats. Then do what you please.