If there's one route I'd wanna see a through-road, and I feel many would disagree, is Adelaide St.
But I would make it a natural street, like Springbank with all the trees, or Colonel Talbot at the hill. Take down as few trees as possible, and have the road surrounded by forest. Something like this:
Have a bridge at the end to bypass the train as well. I feel it's a pipe dream but who knows. With the new Veterans extension, years before they ever planned it, I came up with the exact same idea when I was bored. Curve the road and extend it to Clarke road. Except I would have made the one part of Clarke a dead end, just for the park there or something.