I am hooking up my compressor on my 69 camaro on the driver side using the alan grove 119L brackets (which had to be grinded down to clear the header pipe btw). In any case, I noticed my aluminum crank pulley has only 2 grooves, one for the alternator, one for the power steering. My Power steering is a double groove and does match up with the compressor, but the 69 camaro vintage air documentation shows the belt going around the crank as well. Do I need to purchase a 3 groove crank pulley or can I just purchase a short belt that would run off the Power Steering pump pulley only? Since the crank and power steering pulleys are the same size they turn at the same speed but I didn't know if this could cause a problem that I am not aware of.

I think you need the 3 pulleys on the crank, that’s the stock setup anyway. There would be too much stress on the PS pump the other way. You'd probably wind up with a bunch of squealing belts, if they stayed on.

Well Vintage Air just recommended the same, that I should have a 3 groove crank pulley, so I need to replace my March Performance 2 groove with a March Performance 3 Groove 6091 pulley, another $83 and I'll have the right setup! haha

Better wait before you claim victory.

In a stock A/C setup you can not use the stock water pump pulley, as it hits the 3 groove A/C crank pulley. Apparrently the A/C crank pulley is about 3/8" bigger in diameter which is just enough for the two to rub together.

Don't know if the same is true with the march setup.

Looking at March site its not the case, this Alan Grove bracket kits places the ac compressor quite far enough away above the PS pump to not have any issues.
But now I am thinking that if I am to get a new 3 groove pulley I might consider spending another $500 and getting the whole serpentine pulley system from March instead for $600 at Summit. Else down the road I will have to buy the kit and then buy a $150 conversion for the compressor where as right now I might be able to get Vintage to swap the new v belt Sanden compressor for a serpentine Sanden compressor. Boy oh boy I didn't anticipate such issues when installing a Vintage Air AC system. First the bracket didn't fit over the header pipe so I took my angle grinder and fixed that problem, then the brackets are nasty steel so I POR15 black them to make them look 'ok', now the issue with the crank pulley not working for my situation, fun fun fun!
March Serpentine Long Pump Standard Rotation:
http://www.marchperformance.com/products/22070.jpg