Here is another type switch I found in Germany, these have the added feature of an internal small light bulb https://pbase.com/9146gt/image/136566789 which illuminates when the switch is in the "ON" position. In my opinion, very convenient as a visual-cue for showing the status of the switch. You can see what I believe is he same switch installed in Jeff Haynes GT https://pbase.com/9146gt/image/128387752 - Jeff, is your switch the very same one I just purchased?

These switches are also correct in three ways, the plastic knob is Black, it has a smooth finish and uses the "Pusch-On/Quick Disconnect" type connectors https://pbase.com/9146gt/image/136566787 as the 914-6 GT. Since I was able to purchase two (last in inventory!), maybe I can use them to control the Driving/Fog Lamps https://pbase.com/9146gt/image/22405016 + https://pbase.com/9146gt/image/22265158, maybe the Roof Lamp https://pbase.com/9146gt/image/22265155, or the "Race Car Number Identification Lamps" https://pbase.com/9146gt/image/22265154. The #40 Sonauto 914-6 GT https://pbase.com/9146gt/factory_9146gt_race_cars_sn9140431020_sonauto40_glenn_stazak&page=all used similar switches, see here and read the description of the photo https://pbase.com/9146gt/image/136586308

DESCRIPTION - Bosch Fog Light Switch, for 6V and 12V, inside with 6V bulb, lights up green, switch total length is 5,5 cm, switch knob diameter is 1,8 cm, Made in Germany, nos, new old stock. The Bosch Fog Light Switch is made in Germany and a classic accessory for VW Bug, VW Bus, VW Karmann Ghia, VW Type 3 and Porsche.