Reducing Ceiling Height from Custom DIY Booth Plans

[CHenkin]

I'm planning to hire folks to construct the booth from the Custom DIY plans. However, my basement ceiling is 7', so I would have to reduce the height of the booth. I'm thinking I'd have to reduce it to 6'8" exterior which would bring the interior to 5' 7.5. I am 5'4 and stand while I record/narrate audiobooks. I'm concerned that a low ceiling may affect the acoustics in a way I haven't anticipated. What issues might such a low ceiling create? Can I compensate with a particular sound treatment? And given how low the ceiling is, would it it better I didn't drop it as low?