Zwickey's have killed a lot of elk, in all variations. The Eskimo 4 blades sound like a good choice, but I wouldn't tell you not to try the Delta's if you're confident in your setup. FWIW, I'd personally use the Eskimo 4 blade or Delta 2 blade given your setup, with slight preference to the Eskimo. I like bleeder blades.
I've used bigger broadheads (read Simmons TreeSharks) for elk, but that was with a 68 lb bow at 32" and the arrows were 750 grains. It worked just fine for chopping through ribs and getting to the offside leg bone. You have a little less juice in your setup, hence my leaning towards the Eskimos.