You might also look at FUN PROJECTS : their modern voltage regulator is built inside the stock Cut-Out shell and continues to sit on top of the stock generator. This gives the authentic 'stock' look, but has the advantage of a hidden voltage regulator. Both this V.R. and Tom Wesenberg's V.R. would be cheaper than an alternator-inside-generator-housing, and work just as well.
Of course, if your car is LOADED up with all kinds of electronic devises, I can see where you might be more comfortable with the fully comprehensive modern alternator. I too, like many of us, find the visual aspect of a modern alternator a bit jarring and noticeably 'out of place'. So I fully understand your wanting to both have it AND to HIDE it.