Rotorheads, I've been lurking on here for awhile now and have read the posts concerning the oil system. Knowing better than to assume anything, I would suggest all of you take a look at the second page of chapter two in your Mazda manual (the factory shop manual, not a Chilton's or Hayne's). There you will find a structural view of the rotary engine oiling system, complete with arrows to show the direction of flow.
As far as Bruce Turrentine's modification of the oil filter pad, the diagram show that it is possible to connect the oil passages going to the oil filter by drilling a connecting passage between them at the oil pressure sender hole. I can't speak for Bruce or his work, but removing those plugs and the oil pressure sender and inserting a flexible wire or using a fiber optic light, you should be able to confirm that this is what has been done.

Rick Girard