That meant succumbing to intense "grilling" by stars Rick Roberts, who plays Layton, and Sook-Yin Lee, who plays Chow — as well as executive producer Laszlo Barna, a giant in the field whose past projects have profiled Celine Dion, Shania Twain and Romeo Dallaire.
Still, there was one thing Layton's widow refused to reveal — the cancer that killed him.
Chow has never identified what exactly led to Layton's death in August 2011, and although Barna pressed her to reveal it now, she refused.
"Cancer is vicious and we decided — I decided and Jack decided — not to talk about the one that actually killed him," Chow said in a recent interview to promote the film.
"We talked about prostate cancer but prostate cancer is infinitely curable. And a lot of men have prostate cancer. We don't want to inflict despair into people that have a serious cancer disease that can take you in a few weeks."
The film "Jack" kicks off in early 2011, about a year after Layton revealed he was diagnosed with prostate cancer.
Boasting that his health has rebounded, he embarks on a federal election campaign to lead the New Democrats to unprecedented wins, achieving official Opposition party status for the first time in the party's 50-year history in May 2011. He died just months later at age 61.
Through flashbacks, the film traces Layton's rocky journey from Toronto municipal politics to the national stage, as well as his love affair with Chow.
The slim Roberts says it required two hours of makeup and prosthetics to make his oval-shaped face appear more like Layton's square-jawed visage.
"There are people I work with who wouldn't recognize me on the street," Roberts said.
Lee's transformation included hair extensions, wearing '80s-era shoulder pads and learning some Cantonese.
"The harder part for me was piecing together her personality," said Lee, a former MuchMusic VJ best known these days as host of CBC Radio's weekly show "Definitely Not the Opera."
"She's a woman of few words — very few words — and even with this litany of questions that we assailed her with she would answer in a very brief (way). And I kept sending more and more questions to her and they were equally as brief. So I just had to sort of lean on my investigative ability as a journalist."
Lee says she spoke with Chow's best friend and tracked down one of Chow's pals from high school to gain insight.
Still, Lee says Chow generously loaned the cast personal belongings, including her clothes, Layton's cane and their bicycle to make the film as authentic as possible.
Lee admits it was "a bit unnerving" to wear the same tailored dress Chow donned for the Ottawa press conference at which Layton stepped down, while Roberts found himself more nervous than usual in handling the film's props, especially Layton's cane.
"I dropped it once and I felt awful," he said. "You feel like, 'Am I holding something that will end up in museum one day?' It really focuses you and gives you a really specific thing to go for, which is pretty rare and great."
Recreations in the film include Layton and Chow's wedding, Layton's triumphant speech the night of the federal vote and the Ottawa press conference where he announces he will step down to focus on treatment.
But there are obvious liberties taken as well.
Chow notes she was not as deeply involved in campaign strategy as the film suggests.
"There were other people that were involved but you don't want to have too many characters so there's a bit of interpretation that way," she said.
She admits to intervening in the production a couple of times when she visited the Winnipeg set — once to disapprove of a floral shirt Lee wore because Chow prefers to wear solids, and another time to encourage actors portraying a pack of Ottawa reporters to be more aggressive.
"That was funny because all the press were behaving in the scene very amicably, very nice and polite and Olivia's like, 'That's not the way it works in news. News scrums are a lot more aggressive. Go for it,'" recalled Lee.
Chow says she was on set for two days and saw several intimate scenes that hit close to home — including interludes in hospitals and romantic moments.
In the film, Layton boasts of beating prostate cancer soundly.
But it's immediately clear he is not healthy — a jog results in a fractured right hip, and once that seems on the mend it's his left side that seizes when he approaches a flight of stairs.
The film doesn't really reveal anything new about Layton's shocking decline, and Barna says those details are beside the point.
"Really in the end it doesn't matter," said Barna, who's now working on a theatrical feature about late Canadian golfer Moe Norman.
"Because the story is a love story, it's a story of somebody who matures as a politician."
Chow insists she gave carte blanche to Barna.
"If you're going to tell a story about a person, you have to tell the story in a holistic way, you can't just say 'OK, this is what sports he did or that's the politics he did,'" she said. "Then there's no point. And there's no reason not to tell any part of Jack's story."
In the end, she says she hopes it moves viewers to do what they can to improve the world.
"If the story can inspire more people to get involved and make our neighbourhood, our city, our country a better place to be then it's worth all the energy and efforts that has gone into it. So I'm looking forward to getting a lot of people seeing it.... and hopefully people would find the story compelling and in some ways push them to make a difference."
"Jack" airs on CBC-TV on Sunday.