I would use one of the two that have the bigger converter 7/16 bolt bosses on them, more than likely they came out of an HP motor made after1962. you need to make sure the splines in the converter match the splines on your tranny front pump and shaft If you can take it to a good local tranny rebuilder that can flush it for you on their machine and see if any debris is flushed out or not and ask them to inspect it for you and see what they say
Mopar change the splines in 1966 or maybe in the early 1967 production year, all the original Max Wedge motors and all the Hemi motors and all the other HP BB had those larger 7/16 converter to flex plat bolts and holes in the flex plates. Not all of them had the same splines inside though depending on what year they were made for The small spline tranny will fit in the large spline converters and work for a while, depending on how you drive it, before it fails
The large spline trannys won't fit in the small spline converters, no matter how hard and long you try to make it fit