I've been saying the same thing about power handling of speakers (double what your amp is rated at for safety) for 19 years. I'm sure I've mentioned it here many times since I joined over a dozen years ago. There are two long threads on this very subject on the TGP and Marshall Amp Forums right now, and then this one here on this forum a few weeks back.
https://www.rig-talk.com/forum/threads/scumback-m75-65w-agi-tale.228190/
After answering the same question on three forums, I get a little short with members, sorry.
On the other hand, you know with a 120w into a 100w cab that you can't be thinking you're good to go, either.
And just because you've never fried anything (yet), what you're proposing here is a voice coil melting experiment.
I just moved from California, you don't need to explain gas prices of $5 per gallon and going up, food (it's half of CA here in AZ), medical costs (too much crap to detail including my own cancer scares in 2008 and a new one I found out about
yesterday), so excuse me while I try to keep you from making a stupid mistake and frying four old BlackBacks that you probably would like to keep intact, correct?
So, with that, I'll just bow out of this thread with another DH quote "Man's gotta know his limitations." Good luck, keep it under 4 on the Bogner.