lets see if i can remember here but i remember ill find the link just give me a minute but you need to get the amt 86 i think el camino and get a 70/72 chevelle kit cause you will need parts from both kits! but you will cut behind the doors and the lower part of the a pillars and do a basic nose swap and modify parts from both kits to fit and i think if im right you would use the chassie from the 70/72 amt chevelle kit! now let me see if i can find that link for you!
my bad its a 68 el camino kit you need and heres the link to sae!
http://cs.scaleautomag.com/SCACS/forums/p/68935/739988.aspx#739988