Lister you have an email.
The best way to ship an engine is to wrap it in plastic and pack it in a cardboard box surrounded by expanding foam. Anybody interested, email me for the details.
I've done it by air freight but the company (CEVA) lost the engine at Heathrow and lost it again at the U.S. end. I got it returned by Fedex but this cost $1500 or so, versus about $500 for the air freight.
The best way is to get the U.S. end to arrange the shipping because it is much cheaper when booked from out there. And I would use Fedex. Avoid TNT because while they quote a good price they use CEVA to do it
DHL were the most expensive at £1600 each way (250kg).
The problem I see in this case is that unless the seller is reasonably bright he might not know how to pack the engine properly. I find that Americans often have enough trouble even correctly addressing a package to a foreign country - the legacy of having a huge uniform domestic market. But I still think that the foam method is safer because it is harder to do it wrong than packing an engine in a wooden crate, which needs the proper mounting points to be picked up.