@Yuval,

I think the closest legitimate Chinese surname to Cohen is Chen 陈。

Anyone who has studied Chinese for a while, (or who is Chinese) would spot it immediately as not being Chinese.

Like Orbital said, mastery of the Chinese language, or at very least some ability in it is what would open doors for you with overseas Chinese.

Although I've run into some self loathing Chinese in the states who would honestly rather you not have the slightest bit if interest in China or the Chinese and just be as Anerican as possible.