The L100's look really good, I'm curious about the guitar to the left??? You have given me hope for a pair of L112's I acquired from a home where they were not loved.
An Epiphone Les Paul Standard. Fit and finish of the Chinese guitar is exceptional. After a year or so, the electronics started acting up, but you expect that at the price point ($400.00 when I bought it). For less than a few hundred dollars I replaced the switch, pots, and output jack. I installed Seymour-Duncan pickups, which have a more mellow and less grungy sound. Tuners and nut didn't need replacing.
It's pretty easy to finish old JBLs. Just remove the drivers and clean out the inside. You can tell how primitive manufacturing was back then. No internal bracing, very minimalist crossover network, and lots of fiberglass stuffed in willy-nilly for damping. Changing out terminals is easy because the box is so big.
The crossover network with pots (such that it is) screws directly into the front baffle, covered by a glued-on foilcal. You pretty much destroy the foilcal taking it off. But facsimiles made of the same aluminum material can be sourced. You can even get new aftermarket foam grills, but they are expensive.
Original drivers are no longer made, but unless yours are damaged, they tend to last forever. My woofer has never been serviced and works like new. Used drivers are probably OK if bought from a reputable source. Most second hand LE25 tweeters have punched in dust caps, but you can get facsimiles from a couple of the major speaker suppliers. They are said to be built to original JBL specs. I bought two, and can confirm that they are drop-in replacements. As far as I can tell they sound like originals.
The veneer on the cabs is quite serviceable, and can be sanded down, stained and/or lacquered to like-new finish. I used 'JBL Blue' paint for the baffle. JBL used that color on some of their larger monitors. I've seen some old 4311s refurbed in JBL 'Utility Grey' that looked really nice, also.
Some people offer kits to 'upgrade' the crossovers. Said to transform it into a 'better' speaker. All that might be true, but then you don't have an L100/4311, do you? So I never bothered with that, since it wasn't what I was looking for.