A 727 TC definately will not work on a 904. I have a 727 and a 998 next to each other in my garage right now, and the input shaft is obviously a much larger diameter. I read through your thread and I can't tell if you mean 998 or 904. All Eagles came with 998s except the 4 cylinder's. A four cylinder transmission will not bolt up to a 258. If you have a 904 from behind a Jeep 258, which I don't know if such a thing exists, than you need to use that year and model to find a torque converter.
Most 727 transmissions have a lockup torque converter. The lockup converter debuted in 1978, so anything older than that is definately nonlockup. I know full size Jeeps 85 and newer definately had lockup 727s. You can tell if it has a lockup converter by looking at the smaller inner input shaft. If about 5/8 of the end is machined smooth, then its a lockup converter. If the splines go all the way to the end of the shaft, except for a 1/8 bevel, then its a nonlockup.
A lockup 904 has 26 splines. A nonlockup 904 has 27 splines. A lockup 727 has 23 splines. A nonlockup 727 has 24 splines.