Can you post how many grooves that pulley has?
I've got a 78 amp alt from an '87 Monte that had the semi-serpentine setup, so if the Camaro alt uses the same # of grooves, I could use that as a bolt in if I think I need a bigger alt.
As it is, I don't have any problems with the electric fan on, heater on high, and headlights on. Not sure what it will look like with both fans on and all accessories on, but I don't suspect it will be a problem.