Rel.28, two things are wrong with your method. One, the flame from that weed burner is hot enough to create lead fumes on the melted surface of the wheel weights. Second, any zinc wheelweights will also melt, completely ruining your alloy. Yes, they are replacing lead with zinc, and steel, especially in comifornia. Oh and a third thing is you won't have a homogeneous mix of alloy, from one ingot to the next.
Best is a large cast iron or steel pot over a high output propane burner.
I've had as much as 75 pounds in this one at one time. All the lead is mixed and the same alloy.