Changing a lock-up trans to a conventional trans/converter combo is done all the time. I just don't know enough of the details to explain it effectively. JW Transmissions here in Florida has been doing it for me for decades. But it does at least involve swapping the valve body, pump and shaft. Nice thing about many of the later lock-up transmissions is that they may have a 2.74 low gear as opposed to the regular 2.45. I don't know how to ID them externally and there are differences internally. But Mopar savvy transmission builders should know what it takes to do it. As you may know, lock-up transmissions have a 3/4" smooth machined tip on the input shaft.
Not sure how the lock-up features would hold up in racing applications, even with a purpose-built converter.
