Use heat from oxy acetylene. and PB Blaster. I would not get cherry red as mentioned, just cycling of hot and cooling with shots of PB in between should do it. It seems to wick it up and in. The small pilot hole on the top side as you said would speed things up and be easy to fill. The trick is to loosen and tighten in small increments.
I did this for a Neon recently for the monster subframe/control arm bolts, which are like 8" long. Took about 30 min per bolt, but better then ripping out the threads in the frame.