I've torn down a LOT of Mopar engines and I have yet to see one where the water pump was driven 1:1 or under driven. All I've ever seen the water pump was overdriven, if not only slightly. Of course, I've not seen it all by a long shot, either. But for any type of performance build, I would want my pump overdriven.
Every single pair that I have (none of the cast pump models) consist of a larger WP pulley, (ie under-driven from a standard cooling engine). I, on the other hand, have never seen the over-driven (read smaller) pulley from an A/C application.