Alternator reccomendations

I had a 78A squareback before I went to the 78A delco 12si. The idle output is quite lacking on the squareback in comparison.

How I would determine if your alternator can keep up is at warm idle with the max electrical load on (fans, fuel pump, headlights, brake lights, etc). If your battery voltage is over 12.8 (which is the voltage of a fully charged battery), then it's acceptable. If it is less, you should really have more output.