Serious wood, Deva!!
Jonny, that's Stig's technique, and I still have a cutting board in my truck, yet to be cut up.
Another high-lift technique is a triple wedge stack. Bore through the face-cut at the height of the horizontal cut, straight through the middle of the hinge, wide enough for a wedge. Go to the back, and bore-in slightly below that, 3/8-5/8", and again below the second. Stack three new-ish wedges without them slipping around, set them, then alternatingly drive them. LOTTA lift, no spit out. Need a wide-enough tree to be able to cut the hinge a few inches.
Guys I worked with would beat over trees with single/ single stack of hard-heads. I'm a fan of spreading the force over some width of the back-cut, when needing a good bit of lift, especially with decayed trees. During the time until the tree comes light on the wedges, from tipping over, it will support the weight of the entire tree on more than just the hinge...when hollow and/or rotten, I believe this can Help avoid the rare failure of a terrible tree crumpling under its own concentrated weight.
Once we were cutting a 5'-ish cottonwood, my co-worker climbed into the stump afterward for a picture that I posted a long time ago. 4-6" rind, nothing else. I kept slamming in wedges as he cut from one corner to the other, spreading the force on the stump, until we pulled it over with the winch.