Shen Hoa 617 back seems to fit fine. Don't plan to use the focal plane shutter. The magic lantern lens I am using covers, but with fall off. Probably will want move focus and depth of field.
Ya can't argue math. 17 cm == 6.7 inches. The opening on the back of a 4x5 Pacemaker Speed is 4.7 inches. What do you plan on putting this back on?