Thank you all for your insights. The kit in question here is an enigma, in that the flash holes on the fuselage (and engine cowling) for the gun blisters are missing, and the kit detail is very crisp. This indicates to me that it was produced before the original molds were modified for the first Bf 109G release in 1969; the very first release of this kit (to my knowledge) was in 1967 as a Bf 109F (the box art is the BoB artwork), and it was usually molded in a very light grey plastic, as was the original 1967 release of the Spitfire Mk I. So maybe a few of the original 1967 run kits were made in the creamy tan/beige, or it is from a foreign release during the same time period. If it was a foreign release, one can only speculate what the box art and markings included in the kit were.
The Remembering Revell Model Kits book by Schiffer might shed some light; I'll have to pick one up. Again, thanks everyone!
Cappy D