I guess you didn't see the pulley thread that's already going-
http://www.nissanforums.com/showthread.php?t=51408
Anyways, I haven't been able to look at other engines to see whether or not their pulleys would fit the CA, I would think the CA16 and CA18 pulleys would be interchangable but if so they should be the same weight/size and that's no advantage. I'm still searching and haven't found much yet but hopefully there's something out there.