That's a good design.
The original Superfly chassis design isn't, as the metal is too thin and it needs some bracing (Perhaps angles bolted to the flats) in order to keep it from bending when it gets thrown around in shipping.
Your method should work, but the most important thing would be to use at least 2" of padding (preferably solid styrofoam sheet) on all sides, and I would ship the amp transformers down, as that's where all the weight/inertia is.
Head shell- Black Tolex, yes? Did I quote you a price on that?
Finally a specific response about the head case / shell...
Also some good advice about shipping it with the transformers at the bottom. I could believe that their weight would bend the chassis down if it were dropped with them above.
By this point of course I was resigned to paying whatever it took to ship the amp out to Flagstaff AZ but I didn't know what some of the other costs would be - see part 21