That'd be fine for a solid trunk in my opinion. But why are the #2 and #3 cuts there? Since the trunk had the big vertical split going through it, I wouldn't cut it like your pic shows. I'd cut out and remove the inside half (the part in the direction it will fall) of the trunk/tree first and then treat the back side as its own tree. For speed and efficiency, I think the small face cut followed by a bore into only the inside lean half, then finally cutting through the backside while in the bore cut is the way to go. Again, I'd have just ripped through the split after making the face cut to make sure it would separate and then angle a cut toward the face cut (the hinge) and let it drop. Wastes a little more wood and takes a bit more time, but that would pretty well ensure that half of the tree will cleanly split away from the other half.
Also, since it's oak with a heavy lean, if it were large enough to justify I would make a bore cut after the face cut and then rip down into the back side of that... to prevent it from pulling a bunch of wood out the middle and possibly twirling it to the side as it fell. Maybe none of this is making much sense, but it seems to in my mind and I haven't had any trees REALLY surprise me yet.
