Need help, can't remove a bolt from my k-member

Today was day 2 in my attempt to replace the power steering box that had begun locking up on right hand corners.

Well today's work ended in a fit a frustration after i was unable to remove a steering box mount bolt. This is the single bolt closed to the driver side LCA. I whipped out my boroscope and with a little maneuvering found that the "welded" bolt had broke and was spinning with the nut. Likely caused by the last genius owner who must have put on all the bolts with an impact gun.(took two people to break loose the other two bolts)

So now what do i do? There doesnt seem to be room to get any wrench in to that nut. :banghead: