You definitely need some play room to install the thing and swap out clear plastic drop tubes for different casing diameters. My L&L bowl edge measures 37 1/2 " above the bench top too, with an absolute minimum of 4" extra required to install the bowl/motor assembly on top of the square tubing stand its impaled on.
I suppose you could mount the bowl on the square tube before bolting the tube to the unit if you had to, but that would be a real pisser of a way to do things and would leave you lacking, as onagoth points out, the room to change out the various sizes of feeder plates (drop in) and add cases (or free jambed ones). If you allowed for 42" total, you wouldn't be overdoing it. Personally, I'd want a foot of clearance or 49 1/2 " minimum.