If he frame has been built up already, odds are it's been faced. You can also tell by the character of the face. Concentric circular tool marks (tree rings) mean it's been faced.

Once a shell isfaced, there's never a need to face again except to possibly shave raised burrs and nicks. (recesses don't matter).

BTW- contrary to the info on Park's site. There's no need to face down to the full circle. Once it's faced 2/3rds or so around, or to where there are three faced areas forming a tripod, the cup or lock ring will be supported square to the axis, and can span the recesses. This issue rarely comes up, but over the years I've seen the ill effects of the I want to get this perfect mentality where BB are faced to where they're too narrow (short?). The record that I know of is 63mm. Believe me, an 68mm BB is far preferable to a perfect 63mm one.