...I've seen that grey color - it was just a color they used later on, in the 80s...white would be a safe bet...at some point the lower part of the pole would have been blue, to the base...

...what you can see of the frame/pole in this pretty cool 1964 Gulf '4 Power' No-Nox commercial is white - the retaining ring, that held the sign on the frame, appears to have been blue:

https://youtu.be/CP0D3VY9Rmg


Looking for better Gulf items: signs, globes, cans and paper - especially porcelain Gulf flanges, and Gulf A-38 & A-62 ad glass...