The general rule of the thumb is if the V-8 engine is painted blue with the valve covers on, then the bolts are blue. The major exceptions: chrome valve coves as a factory "option" (aka HP engines) then all the bolts are cad (or dull zinc as a close replacement) plated; sometimes the wiring J-clip bolts are cad plated on blue engines. (1965 V-8 Engines are black.)
Jim