Sorry i dont have pics right now, but in this months issue of Motor Trend there is a GTO tuned by Lingenfelter, it has from 450hp to more then i believe 600hp. Ill try to find pics.

http://www.lingenfelter.com/performancepontiacgto_topend.asp

cant find the other 427-cube GTO package on their website, that is mentioned in the motor trend mag.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=2482998547&category=7244