It wouldn't hurt to do a full reseal including head gaskets (and don't forget the head bolts as well) while it's out. Getting parts from here in the states and having them shipped over will still end up cheaper than getting the parts from Subaru dealers there.
At the very least, rear main seal, rear separator plate, all vacuum lines under the intake manifold, I'd strongly suggest valve cover gaskets and spark plugs, and possibly do the front end service right away as well. (though this last one is still easy enough to do with it in the car.)
Edit: Have you ever had or can you get the current parts engine running before pulling it? Make sure there are no odd noises, etc.
