Need help removing the flex plate bolts

[Hocrest]

I'm in the process of putting another engine and trans in my pearly. The engine went in yesterday. While under the car today, getting ready to install the trans, I noticed that the flexplate was cracked.

I figure no big deal, but the damn bolts are on so tight that I have rounded corners using a 6 point socket and cracked a socket using a breaker bar

I started soaking them down with PB Blaster this afternoon, I'll soak them again later tonight and try to get them loose again tomorrow. If the overnight soak doesn't work what is the next step to get these bastards out??? I still have the crane handy and the engine can come back out with little work.