Hi mate,
The most current (digitally optimized) Pentax 645 lenses are designated D FA.
DFA don't have an aperture ring
FA series has an aperture ring.
The DFA image circles are also slightly smaller than the previous FA series.
Neither the Mirex or Zork adapters have electronic contacts so you cannot control the aperture this way.
There is a manual leaver on the rear mount that controls the aperture, so I suppose you could stick this at a particular point?
I'm also interested in this, so let me know how you go.
Cheers
A