6x7 with Sunpak 4205G
I have never tried this combination before, I would normally use the Sunpak with my K-1. TBH the 6x7 and this flash unit are both so heavy that the single screw fixing is inadequate, and if I were to use this regularly I would make an aluminium plate that would sandwich between them and allow a second screw into the second tapping in the 6x7 body.
The Sunpak 4205G (in Europe, as the GN is 42 meters) was also called the 544 (in N America?). No TTL or dedication (obviously not with the 6x7 anyway), but I can set the shutter to "X" myself, and film era TTL flash, one of the modes in the equivalent Pentax AF400T, is of no use on a modern DSLR.