I can't speak for the bridge but a '59 neck sounds nothing like the Classic '57 in the neck....I found the Classic '57 to be vastly superior for myself.....it was clearer and sweeter sounding without the muddy horrid boomy bottom end the '59 always gives me in the neck. I was pulling some beautiful sweet neck tones with it.
I don' know what the closests SD would be but I'd be hesitant to say the '59......I think it would have to be something with an A2.