Hotwire has a kit out there for NAG1 use in a GenIII swap. The NAG1 is more difficult to swap because the TCM is separate from the PCM, unlike most RFE applications. This requires the FCM to regulate the CAN bus so the two can talk, not to mention all the other inputs from the CAN bus the NAG1 requires to not go into limp mode.

BlackFish, what car did you put the 545 into? Any build pics, or thread somewhere? Any pitfalls/problems you encountered? Thinking about doing a 545 behind a 5.7L in a 73 Ebody.