Like the others suggested, I'd go for a 'mog - something like this:
http://www.unimogsales.com/unimogforsale-U1300L-1987.html
If he's set on an American truck, I'd forget a "true" monster truck because it's a purpose-built racing machine that would be useless for his application. Just about any builder could provide a lifted truck with simple mods like big tires and a flat bed that would fill the bill. The engine wouldn't even have to be modded except for a loud exhaust to create the illusion.
First, find out the import laws for the EU. Choose a truck that fits the best to their specs.
There may be a couple scenarios. One is if the destination country places a value on the completed vehicle for tax/tariff purposes. In this case, I would have a builder make a "kit" truck with all the engine and suspension mod parts and larger wheels shipped in a container to be assembled by someone over there. The other scenario would be to simply build a truck here to your Uncle's specs and ship it "ready to roll".
I would also pick something like a small block chevy powered truck because I think, even over there, SBC parts are fairly easy to come by.