your 73 should have had a 26" radiator as a factory option so all you need to do is get the appropriate tanks brackets and radiator and you should be good to go, i wouldn't think there is any cutting/welding etc even necessary! I have a 2-row 26" radiator from a 78' volare 318-4bbl factory a/c car for sale, if you're in need shoot me a PM. -Dan