I would also recommend googling the US Mustang V6 scene before making a decision. It is often reported that a tune was ok to good, but the rev hang issue was still present, if maybe a bit less. First I would test drive the car as is. Some roadster owners report that their car has no problems with rev hang, but who knows how little sporty driving these people do.
What I would personally avoid: an expensive work around. For example, I would not change the flywheel because it is just fiddling with symptoms.

https://www.mustang6g.com/forums/threads/best-tune-to-get-rid-of-rev-hang.25309/

Here above is just one example of a discussion, reading the 5 pages I would recommend just to show that it is not that simple!
It's not that you can select any tuning and think everything is ok now. The thread is 6 years old. Maybe by now there is much more experience on the subject.

'14 4/4 graphite grey