My club does a lot of PRB long range shooting at various yardage, 150, 200, 250, and 300 yards. Speaking only for myself, I use a .45 x 36" Green Mnt Barrel. My load is a patched .445 RB over 65 grains of 3fg Goex.
I am shooting at 4000+ feet above sea level and my elevation required on the 300 yard gong is in the neighborhood of 102 to 126 inches high from the center of the 24" gong.
With a good spotter, (I highly recommend one) it does not take that long to get on target. You learn little things like refernce points to aim at beyond the target, then come across until you are above the target and let fly. Works great on calm days with no humidity.
The Lyman book is a good reference book to start out with... However, it was compiled at 800+ feet above sea level with high humidity. These condition do play a big part in long range shooting. That's what makes it fun. On humid days I'd have to aim just about the same elevation as the Lyman book calls for.
On the 300 yard gong out here you can normally count; one mississippi, two mississippi, three misssss - "bong"... Pretty cool!
On windy days it is just a chore to get on target and stay there... You really learn how to read the flags that's for sure! I might add we do this with open iron sights by the way, no adjustable peeps allowed... You may choose your shooting position however; prone, setting, kneeling, offhand... No slings or artificial supports allowed!