Done a Euro trip last year to Austria, turned out I needed none of my spares, but had alternator issues so take some contact cleaner, fan belt, wouldn't bother with spark plugs(you can get them everywhere) but take a spare coil, rotor and points if required possibly a cap as well. One tool I would definately take would be a small but good multimeter.
Most of my probles always seem to be electrical the mechanics of these engines are pretty strong, take other usual spares oil, bulbs, fuses etc.
Youll have a great time.