I have seen 2 Chevys with a chrome package on the 6 cylinders. The one I owned was a 64 Chevy 2 4 door. The other was a 68 Chevelle 300 model. I am sure these were a factory option. Valve cover, air breather lid, dip sticks for both engine and transmission and the vacuum and fuel hard lines and flare nuts.
Amazon shows two choices for valve covers Speedway shows three including an Edelbrock valve cover with Edelbrock stamped in it that might be a bit heavier than some of the others. Sad photo though. Edelbrock 4477 Signature Series Chrome Valve Cover Set, Chevy L6 Or at Summit Edelbrock 4477 Edelbrock Signature Series Chrome Valve Covers | Summit Racing Speedway just shows their chrome side covers Chevy 6-Cylinder Side Covers Summit shows Transdapt that you can probably order at O'Reilly's. CHEVROLET Trans-Dapt Performance Products 9342 Trans-Dapt Performance Chrome Engine Side Plates | Summit Racing