Great idea, welding the scrap metal to the stuck BB cup. Never saw that before.
About the aero bars on the commuter bike---back when that model was popular, some people (including me) found the rattling of the spring-loaded arm pad assembly in the up position annoying. One easy fix---zip-tie them to the handlebar. Since you're using them with flat handlebars, it's not as if you'd be giving up any useful bar real estate.