Ken put an Aguilar OBP-3 in his L-2500 and seems to like it. The big thing for him was that he didn't have to cut on the body to make it work, so he could take it all back to stock if he wanted to.
On the other hand, I put a
Nordstrand 3b in my NotAG&L approximation that has L-series pickups in it, and I do really like it. Not that I take it off of flat all that often, but it's nice to have the flexibility if I ever want it.
As for a tech, I got nothin'. Your best bet would probably be to do a Google search for your general area and include the term, "luthier," and see where that gets you. That's how I found the shop that I've taken my bass to.