Ohhhh

, this one?
My first thought then would be the T/I "JF324" set, i.e.,
Jazz Series,
Flatwound,
32" scale,
4 string set. I'm a little
biased towards T/I's

. I've got them on a Yamaha 260F
with a hot P type pickup. That big ol' "Sidewinder" on the
EB-1, though, has a reputation for bein "muddy". Hmm.
The option then would be the J
R324. But roundwounds
on a rosewood board? Ahh! Decision, decisions

.
The "outta' left field" option is to replace the pickup with a
DiMarzio Model One or Will Power Neck model

.
I think it depends on the tone you're goin' for. The T/I's are
a light gauge - low tension set. They can be very articulate
in the lower registers, so I don't imagine there'd be a problem
with gettin' muddy. For pure unadulterated thump, you could
try Rotosound RS88M tapewounds (M for medium scale).
Roto also makes the RS77M - "Monel" (not nickel or s/s)
medium scale flatwounds. LaBella 760FL-M are stainless
steel, medium scale, flatwounds. The s/s may be a little
brighter than say, the T/I nickels.
Somethin' else to consider if you're tryin' to get a brighter
tone are the "hybrids"...half-round, ground-round, pressure-
wound, etc. Easier on the fretboard than all-out roundwounds,
and a little brighter than regular flatwounds. D'Addario s/s
"½ Rounds" are available in medium scale, as are GHS
"Brite Flats" and "Pressurewounds".