Just a thought, depending on your budget, you may want to consider a Schneider apo-Digitar, SK35mm. This means moving to a tech camera, but by far this will give you the best results in the 35mm Medium format. The SK35 is an excellent lens, and on a P65+ you can get about 8 to 10mm of shift. This means moving to a tech camera but if you want the sharpest 35mm, or any wide on a medium format, then the tech camera solution (Alpa, Arca, or Cambo) may be where you want to look.
I don't believe either the AF, N or newer Phase One D versions of the 35mm F 3.5 will get you close to the results of the SK35 on your P65+.
Paul Caldwell