Not sure, but plumbing supply houses used to sell lead in five pound increments. I don't see any reason why they wouldn't still have the lead. Plumbers use the lead to seal pipe joints in cast iron pipe. For those not familiar with the method, it goes like this. Basically you have a propane tank, not too different from the barbecue type. On top of the tank there sits a burner mechanism with it's propane supply hose connected to the tank. On top of the burner sits a kettle. The lead ingot was placed in the kettle and heated until it is molten. Then the plumber dips a ladle into the molten lead and pours it into the pipe joint.
Bottom line here, Mike, is that the lead ingots are roughly a 3" square cube. It wouldn't be too difficult to drill holes into it for eye bolts. Then you could hang it from the bridge.
