So, there is a speed where Drag is at a minimum for the Lift being produced, thus requiring the least amount of Thrust from the engine, and, for piston power, that is the speed that will result in maximum range
Dont think so.
Minimum drag is normally associated with minimum power required, and therefore best endurance.
Best range on the other hand, is found at the TAS where a line from the origin of the (Horespower Req'd/TAS) graph meets the Horsepower Req'd curve as a tangent to that curve, and therefore gives the best ratio of TAS versus HP req'd (and therefore miles per fuel burnt)
It is normally faster than best endurance speed.
....and isn't this what we call Full Throttle Height?
correct.