Installing Vintage Air and need Pulley Help

[doodah man]

I'm installing the VA AC system and they don't include the crank pulley or belt to run the AC.

I've got a short water pump, power steering and the alternator on the drivers side. I'm trying to figure out what I need to replace.

I've attached a picture of what I have now. Is the crank pulley that's on there now two pieces? If so, do I just replace the one nearest the alternator with a 2-groove pulley and re-install the one driving the PS? Or do I need some special 3 groove pulley? I found a two groove crank pulley on GM Parts Direct (PN 3744043) but I'm not sure if that's what I need or not.