As a matter of curiosity (mine, if no one else's), I checked to see what the cost of individual pieces of the Engine Dress Up Kit would have been versus the complete Kit (C7OZ-6980-A). For this, I used my May, 1967 Ford List Price Book. The individual pieces (Cobra Valve Covers, chrome dipstick, chrome radiator cap, chrome oil breather cap, and air cleaner with chrome lid) totaled $101.50. If one purchased all except the air cleaner, the total would have been $ 74.95. Compare this to the cost of the complete Kit at $79.65. Thus, for about $5.00, one would get an "extra air cleaner", if he already had one, plus a few small pieces of hardware.
In putting the cost of the individual pieces together, I found a couple of interesting items related to the Valve Covers. As noted in the contents of the Kit (a copy from the 1967 Parts and Accessory Catalog is attached), show that the Valve Covers were C5ZZ-6582-B (LH) and C4RA-6582-A (RH). In looking for the prices of the two Valve Covers, the Price Book notes "Serviced as a Kit only". This means that "technically", the Valve Covers couldn't be purchased individually, but only as a KIT including both right hand and left hand. this Kit (C5AE-6A547-A) listed for $46.70. Also of interest is that sometime between July 1966 and July 1967, this Kit was designated "NR" (Obsolete).
The complete C7OZ Dress Up Kit was designated as "NR" sometime between January 1972 and July, 1974.
Also, since Scott brought it up about the Chrome Valve Covers, I checked the List Prices on them. Both the LH (C6ZZ-6582-D) and the RH (C6ZZ-6582-C) could be purchased individually for a "whopping" $9.85 eachj. The non-Chrome ones (furnished in primer), in contrast, were $5.50 each.
Bob