he return of tour captain Alun Wyn Jones to the fold last weekend despite dislocating a shoulder only three weeks prior has given head coach Warren Gatland a real selection headache ahead of the game in Cape Town.
But Best, who toured alongside all three in 2017, thinks that Henderson and Itoje, with a fit and firing Jones coming off the bench, is the winning formula.
"I think (the selection) will give you a big indication of how that shoulder is,” said the former Ireland captain who has teamed up with Specsavers this Farm Safety Week, to highlight the impact that excessive noise exposure can have on your hearing.
“If they're not sure at all I think they'll start him because they can't bring him off the bench for him to potentially break down.
"If you felt he was good and you could bring him on with 20 or 30 to go and be sure that he would last, I think that's ideal.
"Being around the squad, being in that matchday 23, you could almost be sure that he could be that leader off the bench to make sure you've impact coming off it.
"When you look at the amount of rugby he's played, even against Japan he didn't last very long.
"More so than that Itoje and Henderson have been two of the better performers for the Lions and when you're in such a tight environment like this you want to get the guys that are in form on the pitch. Alun Wyn I think will have a big role in this Test series but I personally wouldn't start him.”
While Adam Beard and Jonny Hill may have something to say about it, Jones as the most experienced of impact replacements would seemingly push Best’s former Ulster team-mate Henderson into a Test jersey, something he just missed out on last time around.
Having witnessed his development from gangly teenage backrower to Ulster talisman at close quarters, Ireland’s most capped front-rower believes the 29-year-old is ready to show he can mix it with the world’s very best.
"Where Hendy's ceiling is can be very hard to tell,” said Best.
"In his own way, he's a big competitor. He produces things that you'd think he wasn't capable of.
“When you see him about the place or you know him, you see him in the gym where he's probably not one of the strongest, and then he gets on the pitch and he looks like one of the strongest people you've ever played with.
“He has this ability to get something out of himself and he does it in a way that is different to others. He doesn't shout and scream like others might, he just goes about it and knows what he's capable of.
"He's a lot more competitive than he probably gets credit for because of his laid-back nature. I think for him it'll be something to be relished.
“Hendy is very much aware of how South African rugby, both historically and now, put so much emphasis on their second-rows.
“It's a massive opportunity for him to come up against Eben Etzebeth and, whether it's (Lood) de Jager, (Franco) Mostert, whoever it happens to be, and really show how good he is.
“Hendy I think, especially after four years ago, really feels that he wants to show on the top stage just how good a player he is and I would love to see him starting."
With Lions assistant coach Steve Tandy saying yesterday that the initial selection meeting on Sunday was “one of the toughest” things he’d been involved in as a coach, the number of close calls is clear.
"There are still a few nailed on starters, Furlong and Murray” added Best of the Irish prospects for good news on Thursday morning. “I think Hendy should be starting and I think Robbie (Henshaw) probably has done enough with what he’s shown and the way the Lions want to play.
"I think Tadhg Beirne is another who’ll start. He gives you size, ability over the ball, he can play in the wide channels, but I think Jack Conan will probably be unlucky with how much faith Gatland has in Toby Faletau.”