Forget cleaver stacking...

(substitute for if no AP for more armor, AP, and Mana but no bonus hp)

With Transcendence and Celestial Insight, assuming primary path is Inspiration (slightly less for sorcery)

700 total AP, 4700 total Mana, 45% CDR, 100 bonus armor, 55 bonus mr, 350 bonus hp.

Keep in mind that Ryze's ability damage scales with bonus Mana - Q is getting ~100, W is getting ~34 damage, E is getting ~68 damage, and empowered Q is getting ~ 170. This may not sound like a lot, but with how rapid-fire Ryze can blast out an undodgeable EWEQ combo, an extra 350+ damage on top of bases and AP scalings and multiplied by abyssal mask is not to be sneezed at. If he can confidently land Q without W snare, it starts adding up very quickly.

I don't know if this exact build will be particularly good, but I think Transcendence has a lot more potential on Ryze than on Black Cleaver users.