I'd try to get at least one line set with the big shot, and use that same line for the pull test. If the tree is still standing after the wind, that should make you feel a bit better about climbing it. The higher you take the top off, the less force either pull or push back you'll be creating.. Sounds like you should be more concerned with the top pulling becasue of the lean of the tree.. I'd use an extremely narrow humboldt with a plunged back cut, leaving a thin hinge, then center bore the hinge and use very little stump shot .5-1" max, unless you are concerned that the top will hang up on another tree enough to push that butt back into your lap. In that case you'd need more stump shot, especially if you were taking out a large top, where it could have enough force to break that weak hinge.
The narrow, center bored, hinge with minimal stump shot will help the hinge to fail before the lean of the top has a chance to pull much forward on the hinge, by making the hinge very weak, so it fails with minimal force. And the narrow notch will have the top seperate before the top gets much lean out in front of the tree, again minimizing pull forward. The only issue with the narrow notch would be again if the top hangs up and then comes back at the cimber after the butt pendulums durig the drop. Then you have to go with a little wider notch.
If you only had to go up less than half way, it would be fun to back guy the top, then set an exra strong fused hinge with a step cut, tie another guy line just below the notch and back cut, then come down and use the line below the hinge as the back guy, and the higher line as a pull line.. Its like a game of chess, makes you really think how to get this thing down the safest, fastest easiest way. I love trees like that..