Shawn,
While the MPC doesn't note any particular information on the "AJ" ink stamped convertor supplied in the K code applications , they DO have a slightly higher stall speed than a "regular" C4 convertor. If you use Jay ( a great choice) ask him for a "mild" increase in stall to 2,000 ( over the 1,800 stock). This mild increase will mimic the original and not hurt fuel economy in any way. I have "cut apart" an original AJ convertor out of my Hertz car and know the internal fins were modified from a "standard" version convertor. The 289 hipo cam was the reason for the increase in "stall speed" to improve lower rpm drive ability.
Randy