I am somewhat puzzled by your description of what camera windows "the C did not have".
That is because there were "Rounded nose" and "Squared off nose" versions in each RF-4 series, depending on which block they were built in. RF-4C had both noses on different serial numbers, so did RF-4E,,,,and even though almost all RF-4B had the "Angular or Squared off noses", the last three had that rounded nose shape that the USAF also used.
The quick way to tell which set of kit nose parts to use is to look for the prism at the bottom of your decal's drawing,,,,,,it that is there, it is a square nose,,,,if there is a larger, smooth window there, that is the rounded nose.
Hope this helps
Rex