Pro Circuits are by far my favorite low-mid pipe...and they pull hard on top as well. But pipes are like oil, everyone has there own preference. I've always ran CPI's are they run awesome on mid.
Stock carbs will run up to about 65-75HP. My buddy runs a Wildcard 4mil with stock carbs and CPI's and it runs very very strong. I'm at 5000FT so big carbs aren't a must here IMO, but down lower I'm sure you would get the most from your motor with some 33PWK's or 34Mikuni's. But to answer your question, yes you can use stock carbs. Kevin would by far be the best person to tell you exactly what would run the best on that motor since he is building it.