for $1500 - $2000, you've got a LOT of options.
you say that the JB3 has to go, personally, I think it's time for the UA-5 to go as well. replace both those with either a modded Marantz PMD-661 or a modded Fostex FR-2LE, and you've gotten rid of one box, and have comparable or better sound, IMO. The PMD-661 and the FR-2LE are similar, both in size and functionality (XLR input, phantom power, etc). But my vote goes to the PMD-661, because it has a few more features (S/PDIF input, auxiliary 1/8" line-in, autosplit files (the FR-2LE stops recording when you get to 4gb), etc, etc). of course, another option is to spend ~$1600 on a 702, but that won't leave you with much money for mics. and most people will agree that it's better to spend more on mics, because a nice pair of mics makes more of a difference.
alright, so a modded PMD-661 will set you back ~$650, which leaves $850-$1350 for another pair of mics. Here are just a few options in that range. There are advantages/disadvantages with each, so you need to decide what is most important to you, whether or not you need the flexibility of multiple caps, whether or not you are fine with full body mics or want actives, etc, etc...
Neumann km184 (full body, fixed cardiod, definitely in your price range used)
AKG 480/ck61/62/ck63 (full body, several capsule options, in your price range used, but maybe not with all the caps)
beyerdynamic MC930 (full body, fixed card, in your price range new)
beyerdynamic CK930 ("active" cables, fixed card (although CK950 hypers are also available), in your price range new.)
milab's (active, in your range new or used)
mbho 603a (active, in your range used, Todd has a pair in the YS right now)
Peluso CEMC6 (full body, multiple cap options, in your range new or used)
this is just a short list, there are many more options than listed here as well. all of these mics have very different sound to them, and you need to decide what you like best (mbho's for example, I really dislike the sound of, but if you talk to "Bean", he'll tell you they're the best mics out there). so you need to figure out which mics you like the sound of, and whether or not you need to have multiple caps or active cables, etc, etc...