Add-on pulley for AC???

[gabe2000]

This is my last change to tried to investagate if adding AC to chevy 250(easy/cheap). I saw at thepartguy.com sells this add-on pulley. This is realiable or has somebody tried this???
My chevy 250 engine is running with 2 grooves pulley but before I a sanden compressor/AC system, I need to know if this possible. An easy solution without adding pulley to Alt, steering pump or installing 3 grooves pulley.
Please look at the pics one is for crankshaft and other is water pulley.