"That would be awesome for charity," Tyson said on "TMZ Live" ... "Can you imagine me and him going in the ring together?"

Of course, 53-year-old Tyson has been training like a maniac recently and looks absolutely terrifying -- something he credits to the stem cell treatments he's been receiving.

"I'm in good shape, I feel really good!"

Now, with 57-year-old Holyfield also training for a comeback -- we asked if there's truth to the rumors they're planning on running it back for a 3rd time.

"Anything is possible," Tyson said ... noting that he's "having fun, looking good, showing off my new bod and stuff."

Tyson says he's committed to living a life of charity and gratitude -- but he knows a fight with The Real Deal could make a serious difference in a lot of people's lives.

"Hey, listen, there are a lot of people out there that need help and something like that could help a lot of people, that's in need for help."

Tyson also revealed he's focusing on meditation -- and feels he's on the path to enlightenment.

In fact, Tyson will be participating in a massive World Meditation Day event Thursday at 11 AM PT ... along with Deepak Chopra and Tony Robinson.

Tyson says the goal of the event -- which will be streamed live on Facebook -- is to get 1 BILLION people from all over the world to unite for synchronized meditation and prayer.