The GOP would probably be competitive in Eastern Europe
um, no. The communists are competetive in much of Eastern Europe.
The GOP is too socially conservative for most of the industrialized world, and socially conservative countries tend to be more populist. The US is really the only country where so many people vote against their economic issues. The only country I can see where the GOP would be a good fit both economically and socially is Singapore, and even there they'd have to tune down on the religious right since Singapore's far right government is still rather secular.