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Yup, 90º is the ideal and I've heard differing opinion on the line being through the pivot and cable mount and the pad/pad mount and cable mount.
Either way, while 90º might not be totally achievable on that VO brake, you could certainly do a lot better than it is in that photo.
@dangeek the brake arms are like a Touring but that cable set up is more like you would use on the wider armed Neo Retro.
I think they're meant to be set up like that. They're like the Paul touring cant rather than the neb-retro canti. It gives better clearance for panniers etc but I guess you pay for that with less braking power.