Hobby, coupla things:
When pulling trees over using a vehicle, consider: If the tires start to slip and you break traction, the tree (if it's heavy enough) can actually pull you back further than where you started, risking snapping the tree off at the hinge when the kerf closes.
In your example of using a block, you actually INCREASED the force required to pull the tree over; since the pulling force was effectively applied (roughly) in between the two attachment points on the tree.
Dan,
In your example I may have used the 3:1 MA system tied to the cedar and gunned for the target with tapered hinge, to be fancy. Since that would pull the tree slightly towards the cedar, it would ensure counteraction to any lean towards the house. More likely, I just would have attached my come-along to the cedar, and then a bullrope directly to the tree being felled. With 20 feet of pull at 4,000 swl, the tree would have to have one helluva lean to not have enough cable to pull it over center.