Knox, have a thread search for the terms ROP, LOP, lean, etc. There have been some great threads on the matter in the past. Mr Chimbu and Jaba in particular comes to mind as posting some great info on those.
Then of course reading through Pelican's Perch. Then reading it again. Then several more times.
The Lyc/TCM references have lots of good info, but also some bad stuff. I've seen pages where the classic CHT/EGT graph is displayed, sometimes even with 50LOP shown as "best economy", but then a warning about "there be dragons here".
They often state a risk of detonation, overheating, and engine damage. Yet, what is the best measure of engine temperature (and therefore internal pressure)? CHT. Which is shown as dropping of sharply when LOP, to a CHT that would require 200 degrees+ if ROP. But don't take my word for it though, I'm just a faceless internet name. The words of Chimbu and Jaba, etc however, I would trust.