Already went down that road. Kind of where I started my audio journey. Plenty of vintage three-ways still out there in decent shape.
If you enjoy refinishing cabinets, soldering-up crossovers and hunting down hen's-tooth drivers, it's a great way to kill time.
I've had AR-3a, AR-2ax, original KLH 5, Klipsch Heresy, Klipsch Chorus II, Yamaha NS-690, all restored or had upgraded crossovers installed.
No big JBLs, though. Never found a pair at a price I was willing to pay for beat-up 40-year old speakers.
A pair of KEF 104/2 beat them all, at least to my ears and in my space. Narrower box with smaller drivers, and a heck of a crossover.
New Magnepans (1.7i) pushed the KEFs out, but not by much. Those old KEFs were something special.
Recently (last year) built a pair of CSS Criton 1TD-X stand-mounts. Running with a pair of REL T7/x subs, I may have a new favorite. Smallest speaker I've had in my room and they sound absolutely fantastic. Again, to my ears, with my gear.
I have a relatively small room and the little speakers just appear to work.
Jury is still out whether or not they will displace the Maggies long-term.