People said i was crazy for doing somender singhs grooves, they work a treat.
People said i was crazy to turbo a carb volvo, it works fine but is still under test so i can't recomend it yet.
my next crazy project will be a 5 speed + overdrive, i need projects to keep the sludge in my head moving.
A/C in a 740, go for it, it's basically a radiator a pump and some controls, a basic on-off system would be fairly easy to setup especially if it's a manual, once it works ok you can start refining.
http://www.familycar.com/ac1.htm
A basic how it works page.