Butted spokes are more about long term wheel reliability then weight or aero. By having more stretch in the spoke the window between a fully tensioned spoke and a untensioned spoke is greater. One way spokes fail is to be loose enough to flex over a large range and thus fatigue crack sooner then if kept tight. A spoke that doesn't meet it's loose state from rim loads (bumps, lateral stresses, etc.) won't get loose enough to flex as much as a stiffer spoke.

More spoke crosses will distribute the spoke tension further about the hub and in a manor that allows more flange material to brace against the spoke tensions. The classic broken spoke flange with radial laced spokes is an example of this not being paid attention to.

10 PSI of difference in a tire will have far more effect then a butted or straight gage choice will have.

Modern stainless steel spokes are not plated. They are consistent through and through. Interesting that back when "men were men" the SS spokes weren't as strong as carbon steel spokes were, the SS materials then were not as well alloyed as todays are.

Before buying spokes of a spec length do untension the rims and check out the rims' natural (with no spoke tensions pulling the rim straight) condition. If the rims have much hop or lateral run out reconsider rebuilding with the rims.

But it's your wheel and only my experienced opinion. Andy