Bust the heads off the stuck ones and drop the foot. It will take the pressure off the stuck bolts and also allow for the PB Blaster to run down the threads. You may still have to use heat to help the PB get pats the corrosion. I know it sounds crazy cut the heads off, but I've had them stuck before and as soon as the pressure was off it was easy sailing. I've also had to drill and tap some, but either way, they have got to come out.

The way it's sitting now, the bolt head and metal are making a seal preventing the lubricant from getting to the problem.