I have alot of 70 footish ash trees on my property and have done some severe leaners the way you mentioned and it has worked but I'm nervous as all get out everytime. I did have one barber chair last fall and next thing I knew I was 50ft away behind a huge beech and the ms460 was laying where I dropped it,Saw didn't get hurt luckily but soon as I heard it crack I just ran like the wind.
Yup, I don't like doing them at all. Not that I've done a lot of bore cutting, but I don't like doing it in hardwoods, especially on a leaner like that. I've had some go earlier than expected, and some hang on for nearly the whole damn cut.
Best answer. Only answer. Couldn't have said it any better.
I 100% support this as well, I'm not a fan of leaners, just because I believe a tree should grow vertical, and crown out. I'll be taking one down today, fortunately I can get 50' in the air if necessary.
Looks like ash and it will chair like lightning if you don't do it right . Like the kind of splitting you will not be able to react to. It will whip around hard when it hits the ground too. You try to bore cut that and you will definitely pinch your saw. I cut timber for a living and this one will definitely kill you if not done right. If I were you I'd hire this one out just to put it on the ground. And I don't mean bubba down the street. See if you can find a timber cutter (not an arborist) to drop it for you. Unless it's cracked or something I don't see how it's a hazard to leave stand. It's a pretty cool tree really.
Definitely have a second person there. On dangerous trees it's nice to be able to watch your cut, and have someone watching the top of the tree. As mentioned though, if it doesn't NEED to come down, just leave it be.