Two horn conversion question.

Does anyone have two horns in their A body vehicle? My 1974 Duster only has one and I'd like to convert it to a two horn (high and low tone) system like I have in my 1969 Charger. Has anyone ever done this? I know that I'd have to get another horn and bracket. Would I need a different horn relay? Is the existing horn switch in the steering wheel hub up to the task? Is there a lot of additional wiring involved, or is it a simple plug and play with junkyard parts from a two horn car? Any and all ideas welcome - thanks. (Photo of car below)

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