Thanks Dan, your information is always appreciated. This photo is after a dip in the ultrasonic cleaner and vapor blasting, but you can see the scratches on the fins that will need to be removed as part of the polishing effort.
To make them pretty just takes a little time mostly. Reworking them to look like Barksdale's company made them is a lot of trouble; ditto all the aluminum intakes they made or the intakes made by Offenhauser. 1963-64 made parts have evidence of many steps, multiple mill table set ups, and lots of hand work. The covers made for Cobras with 1964 model year engines were all made off a single wooden master pattern. Raw castings were cleaned up with hand files and machined to create oil fill tube and PCV valve versions. The insides were chemically polished to a slick surface. The outsides were media blasted to create a fine dull matt finish and then sealed by something. Raised appearance side features were polished. Oil fill tubes appear to have been hand made in a set of processes that cut pieces of preplated steel tubing to length and added the SAE type beads with something like a Parker® tool set. It appears some type hand tool was used to lock the oil tubes in place. Unmolested oil fill tubes have all the evidence of all the steps required to make and install them as artifacts.
Circa January 1965 the whole manufacturing scheme was changed and many fewer steps were applied. Multiple new wooden patterns made to revised designs so that oil fill and PCV sides got their own castings meant less machine work was required on raw castings. Oil fill tubes were redesigned and became machine made it appears. The internal chemical polishing was dropped. The external matt texturing remained but to me the covers made 1965-66 were much more variable in appearance of the finish with some covers being quite bright fresh matt aluminum day one while others could be a medium gray color.