I would say significant stock is at least an amount that doesn't make someone think twice about the package. If the founders are holding 80%, then everyone else is pretty much an employee not an owner.

There's nothing wrong with being an employee. There's nothing wrong with working below market rate in exchange for some equity. Just be clear that it's a job and the only way you'll achieve market rate compensation or above is with a significant exit, limited dilution, and good-will toward you on behalf of the major shareholders.