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...if you are building wheels for something like a bicycle with an additional electric boost motor, and to carry the load of you on an XXL frame, along with whatever baggage you decide to haul around, it just makes sense to get the fattest elbow in there that you can. There's some piece by the Wheelsmith guy. on how they now feel that the cross sectional diameter at the elbow of the spoke seems to be the biggest factor in longevity, but I can't find it now. Maybe Google will be more friendly to you than it is to me this morning.
For a regular bicycle wheel, of the sort I build here for my own use on road bikes, matching the spoke diameter to the hole diameter has always been a non issue. But that's not what you are doing.
Here is a reference to spoke selection, but it is not the one I'm thinking of. I'm not 100% sure I'd use butted spokes in your motor driven wheel, either, because of loading and stability.