Best grade of Zamak for electroplating

Dear all,
Hi,
I'm working in a leading lighting industry in the middle east. We are the manufacturer of official, commercial and industrial lighting fixtures.
We are going to produce a new downlight fixture which one part of it (the ring) can be produced by aluminium or zinc die cast. For aluminium part, we are going to paint it in white or black but for Zamak rings we are going to electroplate it in different color. As we don't have any experience regarding Zamak parts, we would be glad to know which grade of Zamak are the most suitable grade for electroplating. (Zamak 2, 3 5, etc?)
I mean the result should be the better visual specification such as bright and smooth surface.
thanks in advance.