Spirit Visage was op, hands down. It just sucks that it's the only CDR item it makes sense to build on laning Zac.
But the sunfire is kinda eeeeeh. Making it break even at level 15, I don't really know. It's still kinda ok to enable pushing on certain champions and less Lee/Vi players rushing sunfire after 1 damage item is kinda good. But on Zac, where the whole champion mechanic requires you to prolong fights, that early damage is crucial. Dealing, say, 6 less damage per second is like dealing 150 less damage through the whole fight where you try to secure the kill. Add the general laning to that and eeeeeeh.
Dunno, maybe I'm overreacting. Needs testing.