JCM 120 are heavy with the stock speakers!
I had an EVM 15L in a (terrible) homemade cabinet as my rig for about 7 years (from high school through college and after). It was a really great speaker and took a lot of abuse, running a mid-eighties ~ 80W solid state Randall head pushed to its limit all the time, before the speaker finally developed a horrible rattle.
A lot of people borrowed that rig from me too, because even undersized as it was, it sounded quite a bit better than most of the other terrible low-budget bass amps that people I knew had at the time :-D So it really got abused.
I possibly could've got it reconed, but the cabinet was completely falling apart too, and I didn't have another 115 cab to put it in, so that was when I finally just got a new rig.