Have you tried 55mm f4? That is a really nice wide angle? I just recently aquired a Pentax 6x7 myself, price was so cheap I could not pass it up. It came with a 55mm, 90mm, 165mm. Wow major mirror slap but still a great camera so far!
Keep Film Alive, Shoot Everyday!
I have the 75mm 2.8, an older one, for my P67II. In 35mm, I prefer a 35mm to a 28mm, so I like the 75mm. I had thought about the 55mm, but I rarely use anything that wide. I must admit though, that the majority of my pictures are taken with the 105mm.