Great stuff on the Izhmash Saiga AK shotguns and other AKs as well. It's loaded with pistol grip conversion info and plenty of other info too. They have an excellent forum frequented by professional builders and accessory manufacturers who are very helpful and willing to give free advice. I don't think there is a better AK site on the internet inspite of the fact that this one focuses mainly on the smoothbores.
No smartass snobs that have forgotten more than you could ever possibly hope to learn, just nice helpful people that share a love for everything Kalashnikov.
http://forum.saiga-12.com/