Tama, if you want the greenish version of Zinc Chromate, I use a mix of Humbrol 78 and 80, for the yellowy shade 74 Linen,a drop of 24, and a touch of 33 or a brown. For the olivy shade I usually use a base of 150, but 155 and 159 are also good depending on the shade you want.
I always mix the ratios to match photos as much as possible, which frequently vary, even within the same aircraft.
If you need any spares for your F4U-7, let me know. I have an Italeri F4U-5N which has seen better days, good for a parts donor atleast.