In terms of Press Cameras, Mamiya Press, not too expensive, but not 6X6, there is a multiback that has a 6X6 option but expensive. Same with Horseman, Lindoff, expensive and the 6X6 backs are hard to find, then again I dont really know if Topcon or Lindoff made 6X6 backs. I have seen 6X6 backs on 2/14 X 3 1/4 Speeds, but the lens is likely either a 90 or 101 that matches the rangefinder focusing arm and the 68X6 is expensive, and none have built in light meters or an option for a metered head like the Mamiya TLRS.