Hi Dan,
Similar to Chez, I shipped a big printer long distance, it was a 7800 and it was shipped in a container from NYC to London. Sat dockside in customs the lot..
It arrived, I opened it, plugged it in, ran a clean..... Bingo..! It worked flawlessly, still does too.
One thing the 7800/9800 printers have is a lever and wing nut that locks the head in lace for transport, if the 7900/9900 series has this, then make sure it's been fitted for transport, it could make a difference.
Good luck,
Steve