I have all the tools to make the floor pans for my el camino myself but I need to have some sort of engineers drawing to make it fit perfectly. Does anyone know where I could find one

where are you located? It might make more sense to start with a cleaner body, i.e. a southwestern one, they are common in yards here. Good luck with whatever you do on your project.

do you still have the floor pans in the car? or are they cut out? maybe you could get the measurements from them or try to find some measurements from some aftermarket ones, or search the junk yeards. good luck