That would end horribly. Briggs may be old with horrible stamina but he is a big dude and the man can punch and is a veteran. No one can just hop over from another sport and survive against him, especially a washed up aging fighter like Jackson.
There is no 185 division in boxing. With the big gloves on, he doesn’t beat anyone in the top ten at 175, even with the weight advantage. This is today and when he was in his prime. He gets embarrassed even worse at 200. Different sports. With the little gloves and with MMA rules, he beats any boxer at least when he was prime. Leg kicks and takedowns, ground game would be hard to defend against. Rampage was monstrously strong in his prime. Didn’t he have a meltdown (roid rage) and some mental issues? I was definitely a fan if his fighting and his personality. If he ever decides to box, I’ll root for him but he will not beat any legit guys. I feel for these guys who make a living fighting and want to stay in the limelight past their prime. Getting punched in the face is a young man’s game. He is a good actor, hope he gets back to that. At least they only pretend to punch you in the face.
He'd be a CW in his prime, but a HW now (no discipline/self control). Huck/Rampage is the fight to make.