Trans cooler

I got a 383 I'm putting in my 69 dart but want to know some opinions should I cool the 727 from the radiator or should I get a trans cooler. It came out of a 70 newport and I'm not sure but belive it originally had a trans cooler because the lines go in front of the oil pan and face pass inner fender. If so how big do I need they have ones on ebay for $40