I don't have any technical info to add, but I bought a Pentax 6x7 with the 75mm lens couple years ago (without TTL) and a pentax spot meter. I would recommend the MLU version if you can get one and are if you are planning to use the slower shutter speeds. I am very happy with the whole system (I now have five lenses and a set of extension tubes to go with it).

The best part (or most entertaining part) for me is pressing the shutter button and scaring everyone around me.

Good luck,