0.9 AP ratio on ult.
What about Bruta, actually?
Brutalizer doesn't build into anything Ez wants or needs. You don't lose much gold for selling it back, but it's probably a better idea to build something else.
When I play as Ez, my build often changes. I'll usually start boots + pots, unless I have a support with some sustain. Or if I want rush an early vamp scepter or phage, I'll start long sword + pots (phage rush is much weaker than is used to be). I would usually buy a doran's blade on my first back (If I don't already have one) or try to get an early vamp scepter. But other posters are right, if you can save up for a BF sword before your first return, that would be ideal.