Heartsteel Synergy Items

Maybe its just a fad, but I'm genuinely enjoying kraken -> heartsteel -> rageblade on Bel on my dia mmr smurf (playing bel in masters vs this invading camille meta is horrendous) and it opens up many possible fourth items that I wanted to discuss.

Which item scaling with HP do we think would suit her best with this build? I'm not sure which does highest DPS between hullbreaker, titanic, overlord's chainmail or sterak's. All need some testing!