While packages have good selling features, nearly all of the best heads I've ever done started out as bare castings. Head Packages almost always compromise some component (ex: locks, retainers, springs, rockers, etc) for the sake of shaving some cost. By the time you upgrade it's a toss-up to where you might have been better to just build them yourself.

Intake port cross section has a big bearing on where the torque peak is likely to occur for a given displacement, peak flow cfm can give you a pretty good idea of how many rpm the flow curve can carry before fall-off and how much peak power you can make. The trend in most forms of naturally aspirated racing (from what I am exposed to) seems to be going to smaller, faster flowing and more highly efficient ports; I guess that's why I was so interesting in trying to get a set of these. I've always been most fascinated in the Technology of engine building, I guess I was just fortunate to find a pair of these at a price that was worth taking the chance for.