Water filter effectiveness for lead removal
Lead isn't soluble in water (although some lead containing compounds are), so most filtration smaller than ~1 micron is typically quite effective at removing lead. Just look for a filter with a NSF/ANSI Standard 53 rating - it needs a 99% lead reduction to certify (link leads to a specific filter, but does list the qualifying criteria).

Other contaminants can actually be much more difficult to remove - I'd assume if any lead even made it to the carbon block, that vast majority of it would stop there.