Originally posted by monochrome Starting with the 67 body . . . ??
Sure they can use old bodies but you have to make them digital. There is going to be more room needed at the back for electronics. Maybe a bigger battery for driving the larger shutter and mirror. Placement of modern motors for shutter, mirror and aperture and AF operation. The dimensions are the easy part, to make a decent package is the hard part. I think the best thing Pentax can do is build a mirrorless body with a mirrorless mount module and an SLT module with PDAF (for legacy lenses). You don't use an adapter but change the entire front of the camera.