Mounted the Frantz filter on this engine for two purposes: 1) clean out debris from engine rebuild and spun bearing, and coke (aka "turbo turds") built up during sludge issues from general neglect by previous owner; and 2) to increase oil capacity and cooling when hot (has low oil pressure issues).
It just barely fit under the coolant expansion tank and I mounted it to some vacant holes on a bracket that supports the coolant tank and some misc wires.
Oil cooler in view at left - brass fitting on the bottom left of it goes to oil pressure gauge, brass fitting on the top goes to Frantz filter.
The return goes to filler cap.
And despite the fact that the filler cap is not far from the PCV port there doesn't seem to be any extra oil going into PCV piping.
The attachment to the filler cap is clearly not the most elegant setup, but I made do with what I had available and it seems to work.