software

Looking for a singing harmonically rich tone from middle
pickup (used alone) on EPI LP Custom. Good split sound
a big plus. The outer pups will be vintage HB vibe.

Heh, going ahead with the project guitar, I see. We'll need to start a 3hb Club soon.

The JB sings and sounds good split. It will be louder and thicker than the vintage style pickups, but if it will be used by itself, that shouldn't be a problem.

I have a JB in my current guitar (bridge position, w/coil cutter) and
its my first choice. I guess I'm just looking for variety, something
else with some amount of broken wahwah sound, lots of harmonics,
but a little brighter and/or a little less powerful to work well in
the middle position and better balance the vintage vibe.

Try a Dimarzio Breed 'Neck' - it's moderate output, very strong lows amp; mids, lots o' harmonics, a bit of vintage vibe but definately not your daddy's PAF :-)

Note - out of box the low end is huge and the 1st string a bit thin but playing with the height of the allen screws helps dial it in. If you want a similar thing but with less low end I'd try a FRED...not as much output but lower in the bass, more balanced amp; not as picky about height etc.