So Arianda can actually sing? If she can sing, they need to cast her in this, even if she doesn't have the belt of say Stephanie J. Block or even Kritzer herself, she would act the hell out of the part in such a way that no one's gonna notice her vocals. Can you imagine her during "Sadie, Sadie" or "I'm the Greatest Start"? She'd be a knock-out.
I love the Anna Kendrick suggestion actually, I hadn't thought about that but she'd be pretty great, IMO.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"