This comment was kind of buried but holds the key: not what you want but what your cofounder and the company needs. I'm surprised they offered to leave you any

This comment was kind of buried but holds the key: not what you want but what your cofounder and the company needs. I'm surprised they offered to leave you any equity; comments about "it should be more" are not aligned with how companies operate. You can be a founder of an active or a dead company, but once you leave you may have "helped found" but you are no longer a founder. Personally I would push for more cash comp and give up all equity. If the company is worth anything your former cofounder can finance your buy-out.