I'd either stuff the inside of the head with tissue paper (or something else really soft and can pack well) or pull all the tubes!!
* I had a Triple rectifier shipped to me in a cardboard box with styrofoam and when I got it, it didn't have a tear or dent on the box but it did have 13 broken tubes (4 preamp, 6 power and 3 rectifier).
* I had a Tremoverb head shipped to me in a cardboard box with styrofoam and it had signs of "droppage" on the box, but the head only had 4 broken tubes (2 power, 1 rectifer and 1 preamp). It also had a new dent in the wooden frame on the left side like it fell on the corner of something.
* I had a Rectoverb Combo shipped to me in a cardboard box with styrofoam and it had every tube broke! (both power and all preamp). And the 1/4 speaker plug was stuck through the speaker .
* I had a Peavey XXX head shipped to me in a cardboard box with styrofoam and the guy packed the head full of newspaper and it didn't have any broken tubes.
Yeah, the amps are tough as hell but the tubes arent. Protect your tubes in shipping the best way you know how! Or if you're going to the same place, take the tubes with you.
I contacted UPS on the first two amps, but they said I'd have to send the item and all boxes and packing material with the driver and it would take up to 6 weeks for them to determine whos fault it was and since they weren't packed by UPS or a UPS store I would more than likely be S.O.L.! So I don't worry about broken tubes anymore, I figure it's gonna happen. I do always tell the person I buy amps from to PLEASE pull the tubes... I've got a T-verb combo coming this week, we'll see how this one pans out.
I always pull my tubes and package them in a padded box and then fit the box in the head chassis and pack newspaper or tissue in it to hold the box steady and from floppin' around and possibly knocking off a transformer or some other important thingy.
I hope I didn't scare the hell out of you, good luck though!