Yes, (if) the engine is rebuilt and there is no problems with it, it is worth the trade and $200. I am curious how he diagnoses the 727 as the torque converter being bad. Perhaps another potential problem with the trans. With that being said, while the transmission is out of the car, it could be rebuilt reasonable or you could use the tranny out of your Challenger. Still it seams like a reasonable deal for you. (If) there is no engine problems.