Best power is about 125F ROP. The fuel flow per HP is about 10% higher than the best economy setting which is about 25F LOP.
Full rich is about 30% worse than best economy. That's the price the schools pay for simple teaching
Leaning till there is a noticeable drop of speed (thrust) and then enriching just a little is probably a fairly accurate way of setting best economy - once you get it consistent.