Dean O'Gorman laughs about one inaccuracy in his portrayal of Sir Ed's best mate, George Lowe, in the television drama
They might have been friends in real life. Lowe was the best man at his wedding. It was to Lowe that Ed said his immortal words after summiting Everest: "Well, George, we knocked the bastard off."
But in Hillary, the 1.98m Ed played by 1.85m Andrew Munro and O'Gorman don't quite see eye to eye.
"George Lowe was actually taller than Ed," chuckles the 1.72 m O'Gorman about Lowe, who was nearer the 2m mark.
"While there are similarities between us, our height is definitely not one of them."
Then again, much of Hillary - a drama series of six parts and a $6.5 million NZ On Air Platinum Fund budget directed by Danny Mulheron from a script by Tom Scott - isn't striving for documentary-like accuracy.
It's more about how Sir Ed obtained his metaphorical stature and the influence of those around him like Lowe, and especially first wife Louise.
"He's not 'Hillary' yet." says Mulheron of the early episodes. "This is what he becomes. I was trying not to make a schoolbook about a hero. He is just a guy. He's a nobody. He's actually a beekeeper from nowheresville.
"He's not the Hillary we think we know until he climbs the mountain. And even then we don't know.
"So I tried to take away that sense of worthiness."
And if that means a lower-altitude Lowe, or a Hillary who's not a dead-ringer for the guy on the five-dollar bill, so be it.
it's always going to be: 'Does he look like this?' And the thing that Andrew had was a great big shy lunk-ishness, which I loved.
"He had the vulnerability and it's easy to play the hard thing but he had something else. He's a big guy and really strong and tall. So he had the looks, which obviously is important. But he was playing a person who is utterly driven but at the same time shy to put his name forward. And he shone."
Former Shortland Street star Amy Usherwood was cast as Louise Hillary (nee Rose) and she, too, exudes the spirit of the character rather than just looking the part, the director says.
"She's got a wonderful old-fashioned glamour about her and she wears a frock terrifically and what she has got is a lovely clarity about her. She just shone [in the auditions] because she had a lovely sort of fresh quality."
The Hillary shoot took some of the cast and crew from New Zealand to Nepal for two weeks, although the mountaineering footage was shot in the Southern Alps, which geologically resemble the Himalayas.
Some parts of Everest, such as the infamous Hillary Step, were recreated in the studio.
O'Gorman found himself and Munro being dropped by helicopter on snowy 3000m peaks in the South Island before heading to shoot in Nepal in places such as Phaplu, where Hillary built a hospital, at 2413m.
They left Nepal a few days before the 2015 earthquake, which killed 9000 people and which would have destroyed much of the old parts of Kathmandu where they had just filmed, Mulheron says.
Filming with a small crew had other challenges and not just feeling oxygen-deprived at subalpine levels.
O'Gorman: "It was really surreal to be working and filming in a place that is completely different. It had its own set of rules and a completely different culture."
Mulheron: "Our first day was disastrous and wondrous at the same time. The bus got stuck in a rice paddy. Everything went kind of wrong to start with and we hadn't shot anything."
But making a film about Hillary - or as he's known in Nepal, local hero Sherpa Tenzing Norgay's Everest climbing companion - helped in dealing with local officialdom, Mulheron says.
Even at the relatively modest local altitudes in Nepal, the pair say, every background shot is spectacular. That's something that accomplished photographer O'Gorman has been able to appreciate - he shared this other profession with Lowe, who photographed and filmed the 1953 expedition (and was nominated for an Oscar for his doco The Conquest of Everest) as well as his other adventures with Hillary.
The series captures the pair's most famous moment together - when Lowe climbed 150m above the expedition's final camp at South Col, some 7900m up, to greet the returning Hillary and Tenzing with a Thermos of tea.
They might have shot the scene in the Southern Alps, but it was still a big lump-in-the-throat moment, O'Gorman says.
"When Drew as Hillary was saying the words 'we knocked the bastard off', I was saying essentially what George Lowe had said too. It really made it quite a special moment for us. The words themselves had carried the weight of that experience for so long, but for me and Andrew it was still an emotional moment."
But if Hillary replicates the triumphs, Mulheron says the series is also striving for something deeper.
There's the love story between Ed and Louise and its tragic end when she and their youngest daughter Belinda were killed in a plane crash in Nepal in 1975.
There's an atonement story too, he says, with Hillary's 1977 Ocean to the Sky jetboat expedition up the Ganges acting as a sort of penance for his feelings of guilt and resulting depression over the deaths. That expedition was filmed for one of the many documentaries about Hillary the adventurer.
The new drama, says Mulheron is about Hillary the man and the making of him.
But why should we, who for many years regarded Sir Ed as the greatest living New Zealander, watch what may be a less than flattering portrait of him?
"Because they are going to see a side of Hillary they never knew," Mulheron says. "And it's the stuff they don't know, what he went through, his romantic life and his relationships, that are just as extraordinary as what he did."
Where: TV One
When: Sunday, 8.30pm