Adding AC to Duster

Does anyone know if there exists a template to drill the hole through the firewall to run the evaporator supply and return lines when adding AC to an original non AC car? Bought a complete factory AC system at Indy last year and was just doing a little research on it. AC was a pretty common dealer addition on these cars, so I figure it can be done with the engine still in the car and without an insane amount of difficulty. Just not sure where the firewall holes will need to be, in this case on a 72 Duster.