Any of the series will work, as long as you get a pair of the same. LE25, LE25-1, LE25-2, LE25-3, LE25-4, LE25-6... they're primarily the same, with only cosmetic differences, for the most part.
Yes, one or two models may be 1 dB different in overall output level than the others... the obvious solution to that is just to turn up or turn down the tweeter level control a bit. That's what the level control is there for!!
BTW: LE 25-2, LE25-4 and LE25-6 use the same recone kit from JBL (D8RLE25-2, IIRC). The others also use a common kit, IIRC (D8RLE25)
BTW^2: NOBODY (including people on other message boards who formerly WORKED for JBL!) has ever found out, AFAIK, why you can't just use a LE25-2 cone kit in a LE25, or similar. Some time, when I actually find one I can sacrifice, I'm going to try installing a LE25-2 cone kit into an LE25... just to see how it works...
Regards,
Gordon.