Alternator reccomendations

Despite what I see in your avatar, I would suggest a Delco alternator, like a 12SI, CS-130, or CS-130D.

I mounted a 78 amp 12SI on my small block and so far it's been able to keep up even with my high amp Contour fan at idle. I have totally rewired the car, but it's very similar to that of the amp gauge bypass. I'm not sure if a big block has more or less room between the bracket and the head than the small block, but they also make these alternators in the aftermarket at 150 amps for about $150. They work really well, very reliable. The CS-130 and later ones have even better idle output, but are a little harder to put on as they have serpentine pulleys.