Honestly, I don't see the need for a Lizardment lore. I think that fluff-wise it doesn't fit (as the standard lores were taught to the Lizardmen by the Old Ones). As for fitting the army like a glove, both the Lore of Light and Life fit like a glove. What do saurus lack the most? Initiative and weapon skill. What does Light give? And the Lore of Life just rocks, resist miscasts, regrow expensive units, make things tougher and harder to kill, and passively heal monsters.