There may not be official records but Govier and others who have 69 registries can give you a breakdown of what % of listed cars are F6. Not precise, but certainly in the ball park. I'd guesstimate that 1-3% came in that color in 1969. You're probably looking at <2,000 cars built and maybe 300-500 surviving as a swag. And the actual number could be as low as 1/2 of that. To get a % from GG will cost you some money.

As unusual as the color is, you see them offered fairly consistently. With over 80,000 RR's built in 1969 that's plenty of cars to start with.

RR69s