You are correct.
Assuming the same things, 62.5 yds or slightly more (maybe 64 yds).
Reason I say slightly more is because the "deer
" doesn't quite exactly cover 8 mils. Looks more like 7.8 to my eyes. Yes, no deer I've ever seen looks that way.
BTW, most deer I've measured are more than 18" B2B. Large muley doe's avg 18-20, mature bucks are 20-24". Most antelope bucks avg 16-18". In real life and extended ranges, those extra 2" are important if we're going to range with a reticle.
Likewise, being as precise as possible with the coverage is important at extended ranges. 1.3 mil vs 1.5 mil makes quite a difference with a 24" buck, 512 yds vs 444 yds respectively......enough to miss or make a poor hit.
This is partly why 500 yds was considered long range in the days before laser range finders. In fact, anything beyond 300 was long range......anything beyond 500 was really long range. Lower BC bullets, no rangefinders, no windmeters, no ballistic software, scopes that didn't track accurate at all when we dialed the knobs, on and on.