Buchanan became a boxing icon, in Los Angeles, in 1971 – exactly 50 years ago - when he defeated Ruben Navarro to add the WBC lightweight title to the WBA strap he'd won five months previously following an epic duel with Ismael Laguna in Puerto Rico.
Taylor is just hours away from following in the now 75-year-old's footsteps should he trump Mexican-American Jose Ramirez in Las Vegas tonight.
Edinburgh's Buchanan, who regularly fought in the States, and topped the bill in Madison Square Garden in New York ahead of Muhammad Ali and the late Joe Frazier, has kept a watchful eye on 30-year-old Taylor's career and was one of the first to pay him a visit at his former home in Prestonpans after unifying the super lightweight division in October 2019.
Buchanan, who suffers from poor health and now resides in a care home, says he would love nothing more than to wake up tomorrow morning to the news that Taylor has come out on top.
"Oh, it would be brilliant, just brilliant if he does it," Buchanan said in an exclusive interview with The Scotsman. "That will be the first thing I want to know when I wake up tomorrow morning is how Josh got on. It would be brilliant for Edinburgh too as it's the Capital of Scotland
"He's going to feel a million dollars when he wakes up. I remember waking up in Los Angeles the next morning after my fight with Navarro and just thinking 'wow'. Everything just went for me. I liked boxing abroad and I had a lot of people who'd come up and speak to me when I was training or at the gym. They'd come and say 'we're coming to your fight, Ken'. If Josh wins tonight he'll have made it right to the top of the sport."
Buchanan continued: "It's unusual for a laddie from here to go and win a world title abroad so to become undisputed would be special.
"It can be difficult to get the decision in America because they are always ready to lift up the home fighter's hand. But Josh is a good laddie and I know he is going to pull it off. Even though his opponent has fought nine more times than Josh, that's not really a big difference.
"You've got to do what you can do. I remember seeing Josh down at Lochend. He was always in good condition then and he looks after himself. He's been well looked after by those around him.
"They're all four good belts so I want to see them when he comes home. I'll look forward to that."
As for one final message from the legend... "Just give it everything Josh. There's only three people in that ring and one is the referee, remember that. You've got the skill to bring all the belts home."