Another dilemma is ESC operation if you use the newer computer. The module is integrated in the newer one, and on the square body, it's a square hockey puck looking thing that sits on a carrier by the MAP sensor and EGR solenoid. I would use the older 7747 ECM on the newer motor and try to setup the Electronic Spark Control circuit on the new motor as it was on the 350. It should just be a matter of putting an ESC sensor on the 454 (not sure if 350 one will work), plug it in, and make sure the knock sensor's in the loop. That would be easier to me than having to deal with the transmission portion of the later ECM. Also, you cannot swap the memory chips between those the older ECM and the newer PCM. The older one uses a PROM and a separate CALPAK for its memory involved operations. In '92/'93 when they became PCMs with integrated transmission controls and integrated ESC, they also combined the PROM and CALPAK into what's called a MEMCAL. The PROM is a small, black, unpluggable rectangle, and the CALPAK is a smaller, black, integrated rectangle. The MEMCAL is a long, blue thing that is completely non-interchangeable with a pre-'92 ECM.
