Yeah, I dont see why not. I don't have an Oracle, but I do have a plain-jane M4 style DPMS carbine, and it shoots pretty well.
Finding a load that will shoot 3/4" might take a bit of work. You'll either have to try out a bunch of different factory ammo or (if you reload) spend some time on load development to get there. I would say 1" groups would probably be a more reasonable expectation.
You can spend a little or a lot on a trigger. I think the best value for a really good drop-in trigger would be a Velocity or a CMC, which you can get for less than $150, if you watch the sales closely.
AR's, in general, don't have much in the way of length-of-pull. That's especially true with the adjustable stocks. However, the flat-top upper on the Oracle will give you plenty of room to mount optics, so you don't have to worry about being able to find the right eye relief. I'm 6'5" myself, and I don't have any issues with it at all.