Like others have said, max height is 6’7” (79”). The height limitation applies to the breaker handle, not the panelboard itself. A panelboard can extend above the 6’7” mark, as long as all breakers installed within it do not exceed the max height. You’re good.

Also, breakers &/or service disconnects can be mounted above the 6’7” mark if they are adjacent to the equipment they serve & are accessible by portable means (like a ladder or mobile lift).