Well, bob will produce 60 fps from interlaced material, but bob on 30fps progressive will produce nothing more than repeating frames, that will be slightly blurred (on first frame lines 1, 3, 5 ... will be interpolated from lines 2, 4, 6 ..., on second frame lines 2, 4, 6 ... will be interpolated from lines 1, 3, 5 ...)
Only good solution would be 24 fps output from the camera (and 25 for PAL would be also useful), if possible of course, which probably isn't ...