Assuming you still have the chain on, the bike in neutral so you are not torquing the tranny (ok, it probably would just turn over, but easy to put in neutral). Foot on rear brake, reaching over the bike, pulling up with your left arm. A helper is great if you have one too.
I had red locktite on my CS sprocket, and it did take a pretty solid pull (using the reach over method and an 25" breaker bar) to get it loose, and then a puller was a absolute must to get the sprocket off.
From what you said about hitting 120 easily I suspect you are already doing that, but trying to give a suggestion. Also, can you borrow/buy a 1/2" electric impact? Not as powerful as air, but might work. Take the bike to an impact? If you use an impact make sure it is in neutral and let the chain hold the sprocket.
Air wrenches take off anything that isn't rusted in place, like spring U-bolts. If you do end up buying air/electric, for comparison a cheap one will have trouble turning itself but a good 1/2" air impact will produce up to 1100 foot pounds of
torque in reverse but won't put nearly that much force into what you are working on, therefore making it much easier to hold. (Ingersoll Rand Ti/Max, or to quote them more accurately, it will remove a nut torqued to 1100lb/ft). Attaining this force would also require optimum supply of air from larger sized air lines.
I do have a 1/2" electric impact (120V one) from Canadian Tire that was only about $50 on sale and it doesn't work too bad around the yard if I don't want to drag out air. I see they have 12V impacts in the flyer, but have doubts as to strength, they are marketed as 'keep in the trunk to change your tire'.
