It seems to be the usual procedure when removing the front leaf spring bolt is to:

1) maybe spray some PB on it2) put a 4 ft long flex handle on it3) bust off the weld nut in the frame
4) start cutting and welding like all those YouTube things.
If you rather not be spending days cutting up your xj try this...

First off, keep in mind while rust may be part of the problem the big issue is that bolt is glued into the weldnut with red loctite. It takes 500 deg f for a couple minutes to break that stuff.
So
1) soak the thing with kroil for a few days, this is for rust, doesn't do anything to loctite.
2) pull up the carpet over the spring pocket and put a wet towel on floor.
3 fire up your oxiacetylene torch with a small tip and a reducing flame ( more heat over less area than a propane torch, less likely to burn the metal with the reducing flame.)
4) heat up the bump/ lump whatever on the inboard side of the spring eye, that bump has the weldnut attached to it.
5) as you go check the temp of the bottom of the lump with your IR thermometer, no need to overheat it and if too cold won't work , try for 500-600 deg.

Bolt comes right out with my SK flex handle and 6 pt impact socket, no guarantees with harbor freight
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The weld nut/thread locker is the easy part.
If it's a rust belt/Northeast Jeep, the bolts are seized in the bushings.

 

For the rust, Freeze-Off is the winner.

 

I have had good luck with a propane torch on top of the small bottles. Heated it from underneath for awhile, put a breaker bar on it and turn a bit, heat a bit, repeat and they have come out. Did that on 2 XJs and worked great. The bolts fusing to the metal bushing sleeve is an entirely different problem.