When I had my house built, we had a bathroom roughed in for a future bathroom in the basement. Where they roughed in the bathroom is right below the heat and cold air ducts, which is below a sunken living room, so at that point my ceiling would be at 6' 5". Other places would be 7' 3" due to the support beam and 8' to the joists where the sunken living room is not.
Will a 6' 3 ceiling be ok? I should mention that it will only be a 3' by 5' section.