Ceiling height requirements to rent out a basement apartment in S

[Matt McElravy]

I'm about to put an offer on a property in Salem, Oregon that has a finished basement. It's on a multifamily lot and I'd like to rent the basement out. It has a full kitchen, bath and bedroom but the ceiling is only about 6'4" and the beams bring it down to 6' in spots. Thsquare footage is included in the home' tax assessment. However, everything I read about making a basement livable space says ceilings need to be 6'8 and now lower than 6'4 at the beams. 

Does anyone know the answer to this or direct me to the right person to ask?

Thanks

Matt