A/C conversion / upgrade

I have a 70 Duster which is a stock 318 no A/C. If I want to add stock AC set up from a doner car will everything bolt up???

I heard that the fire wall cut outs are diffrent from a non-factory AC car and one that had it as a dealer option. Is this true? Solutions? I live in Arizona and AC is getting to be a must for me. Thanks in advance.