I don't think I would worry too much about the orientation of the regulator and its fins. The change from the early cars to the later ones was more that the location changed from bolted (via rubber bobbins) on to the crankcase to being mounted to the chassis. The idea being less vibration getting to the regulator. The reality was a possible and arguable slight improvement in longevity but it would have been more down to less flexing and chafing of the cheap and nasty cables that the original regulator is fitted with.
I'll add that when my first regulator failed I fitted my cheap and nasty Chinese eBay special HD clone which performed admirably for a short while till the car was back at the factory for an unrelated warranty issue when they in turn replaced it with a shiny new original spec one. This lasted rather less time than the original and was in turn replaced again with the C&N special which is still giving sterling service rather a lot of miles later. I do have a second C&N regulator wrapped in bubble wrap and a zip lock bag bungied into place below the front cowl just in case of anyone tempting fate...
