Ain't That A Shame would be a poignant winner as trainer Henry de Bromhead's 13-year-old son Jack was killed in a riding accident last September.
Blackmore is bidding for her and de Bromhead's second National winner after she became the first woman jockey to win the race on Minella Times in 2021.
"Ain't That A Shame has a lovely profile for the race," said 33-year-old Blackmore.
"You're just hoping that you can get into a nice position and find a nice racing rhythm over the first few fences."
The pair not only face 38 rivals - Escaria Ten was withdrawn early Saturday - but 30 daunting fences and the toughest run-in in racing where many a dream has been broken.
It was there, yards from the post, that Red Rum passed the bold front-running Australian star Crisp, who had built up a formidable lead 50 years ago.
Red Rum, who went on to win three times, is buried at the winning post which race management hope will welcome the winner of a trouble-free race at around 1630GMT.
Activist group Animal Rights have vowed their 'biggest action yet' will 'cancel the Grand National' by forming a human barricade across the racecourse.
Police say they will deal "robustly" with any disruption.
Ain't That A Shame - one of 26 Irish runners including another de Bromhead entrant Gabby's Cross - would be the latest fairytale winner in a race that has thrown up many.
'A big day'
He is not, though, the only potential tear-jerking winner.
Irish trainer Jessica Harrington has been undergoing treatment for breast cancer and runs Lifetime Ambition.
"The horse is in great form and is aptly named as it is my lifetime ambition to win the National," the 76-year-old told AFP.
"It is an absolutely iconic race."
Harrington is vying with compatriot Patrick Griffin, 81, to become the oldest trainer to win the race. Red Rum's handler Ginger McCain was 73 when he saddled Amberleigh House to win in 2004.
"He (Patrick) has been there and done it, and is just an out-and-out horseman," said James Griffin, his son and assistant trainer.
They send out Roi Mage.
"This horse was bought with one aim, and we're there now," said James Griffin.
"We would love Dad to have a big day - and it might be Saturday."
Patrick Griffin, like Harrington, will not be present. He has mares about to foal. Harrington, who said she will "be screaming at the television", does not wish to risk catching a virus.
Harrington and Griffin have just one runner apiece as does 2000 winning trainer Ted Walsh with Any Second Now, third in 2021 and second last year.
It would be quite some 73rd birthday celebration if he goes one better.
Their compatriots Willie Mullins (who won with Hedgehunter in 2005) and Gordon Elliott have five runners each.
Elliott's Delta Work - whose owner Ryanair boss Michael O'Leary will be watching in Portugal - is competing with Ain't That A Shame for favouritism.
A more popular victor for three-time winner Elliott would be Galvin as it will be the final ever ride for his jockey Davy Russell.
The 43-year-old - who rode O'Leary's Tiger Roll to successive National wins in 2018/19 - came out of retirement to help Elliott when his stable jockey broke his leg in January.
Our Power will bid to give Wales their first winner in the National in 118 years since Kirkland prevailed.
It would give part owner Dai Walters a fillip as he only recently returned home from hospital after fracturing his back and neck in a helicopter crash last November. Trainer Sam Thomas escaped unscathed.
"They didn't think I'd pull through, they said not many would have survived pneumonia, Covid and sepsis," Walters told The Daily Telegraph.
"It's nice to win any big race and it is one of the biggest."
