55 is PLENTY of space for the EBJD alone but that will not be enough space with another large fish in there.
JDs are plenty aggressive themselves, I wouldnt worry so much as to what species it is compatible with, I'd be focusing on making sure tankmates aren't significantly larger to start. A JD will hold its own with about anything once it grows some. Mine (9" and about 6 yrs old) lives with 4 turtles and runs the show, he has for 5 years. (That all being said, I am assuming the EBJD's behavior would not be different from a standard JD, i've never owned an EBJD)