4100 Questions

I just picked up a Ford C4AF-R 4100 carburetor that looks that it may have never been apart. It has the brass floats and the little "dams" that limits flow to the rear of the carburetor. I also have a parts carb with the black plastic looking floats. I was wondering if I should use the brass floats or the plastic looking ones? Also, should I remove the "dams" and allow better flow to the rear? What is the purpose of these "dams"?

Thanks;
Gregg