They're no help with your particlaur donor vehicles, but the standard would be Smyth Performance.
www.smythkitcars.com/
The closest match would be their Jetta/Golf kit. Here are the parts they use laind out:
As for the aerodynamics -- You could take the whole roof off, or do a slant chop. An aerolid might be improvement over the stock top. Else you could do a half-tonneau.