Richard,
My hats off to you for venturing into the sign trade. It's been my life for thirty plus years.
There isn't a gold paint that will reflect like the real thing. One Shot does have a good option is's known as "Brass". Much better than their Gold. Buy it in half pint quanity.
Applying 23K takes some time to learn. For a gold size, I'd suggest One Shot Ivory. It has to dry three or four hours prior to application of gold.
Good luck.
Joe