72 would probably be even better.
Barn door height.
Measure across for the width and from the top of the casing molding to the floor for height.
In this example the total height is 83 when closed over the opening the door will cover all of the casing for a cohesive look.
The graphic below simulated a door over the opening.
Generally most standard barn doors are approximately 36 x 84 or 42 x 80 with enough extra lip to overlap most standard door frames 36 x 80 by an inch or so.
Add 1 to 2 per door for overlap depending on privacy needs.
Most barn door sizes fall anywhere between 36 wide on the shorter side by 96 tall on the longer side.
Barn door measuring guide for door openings with casing molding.
Always remember that your barn door railing system should be at least double the width of your door frame possibly longer if you have an odd shaped door.