were these left bare aluminum or were they paint orange for the Z28 ?

 

If I remember right bare aluminum.
My roommate back in the mid '70's had a '69 Z28 that I drove almost as much as he did,he liked to drink too much. lol
I just Googled DZ 302 Z28 motor and clicked on images with my PC,every picture is bare aluminum including the dual quad cross rams.

 

Welcome to the club, Chuck.
As said, bare alum and has '372' for the last casting numbers and a Winters foundry emblem cast in, several circles with a W in the middle.