I would be grabbin' my 3/4" impact wrench @ full pressure to remove that one. I think it would be OK to reuse the bolt one time, but I'd inspect the threads and use some threadlocker when I reinstalled it...
My 3/4" SNAP-ON impact wouldn't budge mine on my LBZ. So I used a 3/4" breaker bar and a 4' cheater pipe. Mine was on the stand as well. I used a cherry picker to support the engine on the stand.
I made a tool that holds the ballancer. I used it while the engine was in the truck and it worked great. It has a short dowel that sticks in one of the holes drilled for ballancing, and the long arm rested against the frames cross arm. It could be extended the the same length as the wrench lever and used in opposing directions.
Use an old flywheel if you have one.. Lock both flywheel together and locate a Trans mounting hole on the adapter plate to lock the free floating flywheel in. I cut up an old flywheel so I'm not lugging the whole thing around, but works either way.