[Shotimes] Rear strut pinch bolt jammed - any ideas?

[Leigh Smith]

George or any other suspension gurus;
HELP - SHO down!
I'm doing a Koni strut install on my 100k mi '94 SHO
It's not rusty underneath, but the pinch bolt is jammed so tight I'm afraid
I'll snap it.
It is un-threading, but the sholder section is so tight:
1) it takes 150-180 lb of torque to turn it. Since the torque setting is like
60 ft-lbs I'm afraid it'll snap if I keep forcing it.
2) The shoulder part is jammed enough that it spread the knuckle open 7.5mm at
the tab gap. I cut the tab off and now have the strut out but not the bolt.
I have tried a 2-1/2 ft breaker bar, mopar rust penetrant, my propane torch,
and a new Craftsman 350 ft lb impact gun. Although I think the impact gun may
be choked down with the 1/4 in line, and I may need to go bigger.
Recommendations?
Should I fix the impact gun line and go for it?
(If it spreads the knuckle much farther I am afraid that will crack.)
Should I pull the knuckle and take it to a shop?
(PIA)
Or just heat the *** out of it since the gas strut is now out of the way?
(might get lucky)
Or just tighten it back up?
(and pray... or ... take it to a shop for bolt removal)
I've never had rust stop me til now...
My 89 never did this with 4 strut installs.
I believe there is some other difference in the knuckle other than just ABS
and rotor size.
Lee