White oxidation on Holley

Most Holley bodies/bowls are not aluminum. They are made from what is commonly known as "pot metal", a combination of mostly (90% or more) zinc alloyed with some magnesium and aluminum. The metal is sealed with that gold/brown colored plating, which helps to stop corrosion. Of course over the years the plating wears off, and you are left with that white corroded zinc. Other than looking bad, there isn't really any harm to it.
The throttle bodies are an aluminum alloy however.