I have a 2.5 lb 4x5 (weight w/ lens). I tried a light carbon fiber pod, but the camera moved all over the place with the slightest pressure, movement of the darkcloth, etc. I prefer to use an old Gitzo Reporter -- twice the weight of the camera/lens, not including the head.

Seems like most large tripod heads come with both size screws (often double-ended), with most tripods having the 3/8" screw to connect the head to the pod.

Video heads are not designed to tilt side-to-side, so if you set the pod up level, that should be no problem. I used one on a 4x5 that had a revolving back -- I would get it close to level with the tripod and then level the scene by rotating the back.