Its been a long time (and I'm into a few beers right now) since I've had a chemistry class, but I'd say that you need to look at the actual chemical equation of how lead reacts with hydrogen peroxide (HO) and vinegar (C2H4O2). From the equation, determine the
limiting reagent. From that you can determine how much of a certian molar solution is needed to react with a certian amount of lead. Google "emprical formula," "stoichiometric calculation," and "molar weight".
Here's a start in the right direction.
ETA: From your anecdote, it looks like hydrogen peroxide or vinegar is the limiting reagent. I'd say that, yes, a higher concentration of peroxide, or vinegar, or both would be more effective. Use the right balanced chemical equation, and you could indeed find out how much solution would be needed to remove 2oz of lead.