I have an '83 hog/rosewood, an '85 fretless ash/ebony and an '87 ash/rosewood. I've gigged regularly with the '83 for over 10 years through countless house backlines and P.A.s. None of mine are crazy heavy; They all weigh in at around 10lbs.
To my ear, the MFD pickups from this era don't have a very strong treble response, so I tend to use strings that have a bright sound. The following strings are my favorites on the L2K over the years. All are nickel roundwound. They all have lots of treble, but differ from each other a little:
D'Addario XL - strong upper mids
Ken Smith Burners - strong low mids
Sadowsky Black Label - very even
LaBella Nickel Rounds - very even, slightly more mids than the Sadowskys
Other strings I've tried did not have enough treble for my tastes.
Stainless steel strings will give you even more treble, but I don't like how they feel, so I've stuck with nickel all these years.
The truss rods from some '80s L2Ks can be a little dodgy so I never use heavy strings on these basses. Typically, I'll use 45-105 sets. Normal, medium gauge.
The cut-only bass control is really the secret weapon on these basses, IMO. Once you start messing around with that you open up a huge range of tonal possibilities. It took me a long time to get used to using it, but now I reach for that first when I need to make adjustments and I hardly ever run it past about half-way. Experiment. It's worth the time spent.
Many people use these basses passive only. I usually use the preamp, but there are lots of great sounds in passive mode, too. I use both, depending upon the situation and what amp I'm using. I almost never use the treble boost mode in the preamp.
I don't really have a favorite amp for these basses in particular. Any good amp will sound good with an L2K!
Enjoy your new bass! These old G&Ls are great instruments.