I think the 71s and my 75 are pretty much the same animal structurally.
The ceiling itself is about 6'4". But you have various things hanging below that such as 3 ceiling lights, the air conditioner and a couple top rails for the bulkheads.
I'm 6'1" plus boots and can stand fully erect without hitting my head on the lights and air cond. But I do have to duck to get into the center bedroom and the bathroom.