da Vinci is making 200mm cranks in whatever spider and bcd you want (double, triple, tandem, etc.) for $250.

The most C&V looking custom crank I know of. They've scaled it up to be stiffer than their clown cranks. Not at all as stiff as the High Sierra/Zinn or Zinn Integrated, but those look more out of place on a vintage bike (ask me how I know).

http://www.davincitandems.com/comp.html