"Any type of uphill slope is going to shorten your steps a bit, but not by 30% unless it's a really rough steep climb."
It seemed on the high side (of high) to me too, with the caveat that mile for mile, and when not walking on forest service road to connect trail pieces --- the PNT is the toughest trail I've hiked. Again, that's "mile for mile", not in absolute terms, but the overall trail quality isn't good. Think in terms of the average tread quality and pitch of the AT, but often not maintained (or signed). On flat, level ground my stride is relatively long; on trail like that, it is credible to me that 30% more steps are required per unit distance.
"I'd love to be able to do something like that someday. I'm still trying to fit in a 5-7 day hike into my schedule. 2 months though, what a vacation that would be!"
Hopefully you can make it happen someday. OTOH, it's a the type of vacation from which you generally feel the need for another vacation when it's done! :-)