There's plenty of companies in the UK that offer rebuilt classics- with so many new parts that they're virtually new cars- or outright new cars built using the original tooling. One of the longest running, don't know whether they're still around though- was a company building new Jaguar MkIIs, with modern features, incl XJR6 supercharged engines. They cost as much as a new 540i back then, with no shortage of takers.
My favourite though is a restorer named Mark Cosovich, who specializes in Merc W123 models. Look him up. There was a similar restorer specializing in the same model in the States, but I can't seem to find him now.
Of course, this is very subjective and depends on your own tastes, country etc, but for me, there's nothing like the old German cars.