Another source for that quantity of lead
Check out the small town newspaper publishers and printing shops. Many of them in years past used to set their own type in the printing galleys using linotype machines. These machines molded type using molten lead. The lead was fed into the machine's melting pot with 40-50# ingots. The used type were remelted in a large gas-fired pot and after removing the ink residue and impurities the lead was re-cast into ingots for the linotype machine.However now with the advent of desktop publishing and with current technology, the printing galleys full of lead type is no longer needed. You might be surprised to find shops that still have the equipment and lead but no longer use it.How's that for a totally-out-in-left-field suggestion? Barring this idea, a good source would be a metal recovery/recycle dealer. Not an auto junkyard, but a true metal recycler.