In the 1978 Pace Car version.  Was the valve covers and engine painted blue on the L-48?  Were the valve covers on the L-82 aluminum polished and the engine painted blue? 

By '78 all GM engines were painted corporate blue. L48 engines used stamped valve covers painted to match the engine.

L82 engines, while having corporate blue blocks and heads, used lengthwise ribbed magnesium or aluminum valve covers painted gloss black, but the top edge of the ribs was unpainted and natural metal color.

Bruce is correct