The shipping containers from volvo etc sometimes come up for sale on ebay, or try your local volvo or mercruiser dealers etc, they will have creates that engines came on that they might be able to sell to you. From what I recall they are a stronger version of a pallet base with plywood box built around it.
You need to make sure there's no collision damage.
Dummy engine beds firmly bolted to a pallet with the engine bolted to the beds, but not using flexible engine mounts so movement is eliminated. Cover the engine in polythene, then build a box with four bits of sheet, using the pallet as the base. The sheet should be lined with more poly.
Squirt builder's expanding closed cell foam into the voids between the poly wrapped engine and the poly lined sheet. More foam to a depth of a three inches on top.
Remove sheet leaving the poly lining stuck to the foam.
You now have a cube of foam with an engine in the middle. Once at the destination just break the foam off the poly around the engine.
When my new engine arrived from the USA it had been drained of oil and coolant.
The engine was coach screwed to 4"x4" soft wood beds, which in turn where bolted to a pallet. The whole thing was encased in a tri-wall box, strapped to the pallet.
Tri-wall is seriously tough cardboard used for air freight. Probably offers better protection than cheap plywood.
For work I occasionally have to ship IT hardware abroad in racks and use a company called P&M Packing (they used to be part of Peters and May). They will produce what you are looing for and deliver.
They are based in Southampton and I'm sure will be glad to help + they are not that expensive. http://www.pmpacking.com/
Agree with all the above. However in addition I would seal all openings (exhaust, air intake, cooling water etc) to prevent dirt/ bugs from getting in. Also drain all fluids and spray with a preservative/ rust inhibitor.
LP Marine in Trinidad are Agents for Volvo - there might be a slim chance that they would have a second hand 2003 engine available for sale. http://lpmarinett.com/volvopenta.html
We bought a new second hand starter motor from them a few years ago for our 2003T.