On my '46, it is surprisingly close. I would consider how far above the bottom of the body the hinge point is. If it's flush to the bottom, everything will move away from the cab as the body goes up, so it can be quite close. If, for some reason, the hinge point is higher, the bottom edge will move forward a TEENSY bit at first and you might want an extra inch or so. In general, I would say to allow as much room as you normally would between the cab and body, maybe err on the side of caution, but you don't need a lot extra.
