Meindert I had a look at your Vampires in 1/72 and the 1/32, very nice builds.
Did you source the information for the Springbok roundel and the Springbok Castle from Wiki?
Wiki has a terrible rendition of these two national insignia which are completely inaccurate, eg. the buck has a too big chest diameter on the Springbok roundel and the Castle's bastions are incorrect as they are too "fat".
Reference is also made to the yellow on the fin flash, the correct colours for the fin flash is orange, white and blue. The orange is similar to BS381C-557 and the blue is similar to BS381C-108.
Ken Smy printed some decal sheets in the 80's and 90's and these had the most accurate copies of the national insignia though the orange is a tad to light on the Springbok roundel.