I just got a really old 5x7 technika. It is all black, I guess a one or a two. It came with a 4x5 non grafloc reduction back on it and i want a 5x7 back for it. Will the back off of the III or IV technikas work? Also, I was thinkin of getting something like the canham 6x17 roll film back for this camera. Might it work with one of the linhof backs? The camera has a a similar rotating feature as all the other technikas i have had with the four sliding clips at each corner holding it on.