I just bought, redid and sold both a pair of Jubal L65s and L100s. It definitely improves the speaker to put in some better hardware and to update the crossovers but I really hated the sound of both these speakers. What they did do well, especially the Jubals, is play loud. In fact in some ways the Jubals made everything sound kind of like a live performance. So before buying any older JBLs make certain you like this West Coast kind of sound. I thought the L100s had absolutely no redeeming qualities. They just sounded odd.
My guess is that there exist much better, more modern representations of what people like about JBL. I am not trolling just trying to help.