I am working on this conversion right now. 3x4 Super D fitted with a 4x5 Graflok back. I have the back on already, and trimmed down so it's not that much bigger. Need to adjust the focus ground glass and compare with the ground glass back, to make sure they are in agreement. I built a new front standard lensboard and quick-change lensboard system to allow interchangable lenses faster and larger than the original. I rigged a prism on it too, so it will be ideal for handheld shooting. It's much lighter than the 4x5 RB, although to save space and weight, I mounted mine with the back vertical (e.g. no longer rotates). All the conversion so far is 100% reversible, with only a minor modifcation to the rotating baseplate piece, which would not hurt or impede any function if someone wanted to switch it back to 3x4. (not that I feel bad about modifying one of these at all, nor should anyone really - they are not uber rare nor in any sort of real demand.) I believe it will cover about 4x4.25 or 4x4.5", give or take. I'll fit mine initially with a 8" pentac f/2.9 but also plan to try an aero ektar on it, and perhaps other lenses. There's a limited focal length range that will work with this camera, depending on the size of the lens. Probably somewhere around 150mm - 210mm or so. I'll post pics and details once I get it finished. I was inspired by Minnicks work, but didn't want to pay his prices plus I enjoy the DIY aspect of it.