Unfortunately, your plan won't reduce the tendency for the bar to fail at that weakened point right between the two bushings.

You've increased the capability of the fastener to secure the bar with additional force (if needed) but that additional force won't translate into additional strength at the compromised location.

In Pete's setup, he has only the bolt to secure the bar. Again, I'm not sure how this functions without a suitable spacer.

I'm quite sure that a spacer outside the cap screw with a drilled and retapped bar will work perfectly.

The way it is now the Stock Bolt ends right where it is weakest. Nothing but an empty Tube past the end of the Bolt.

I live in a State and location with no Salt on the Roads during Winter so the rust is going to proceed at a slower pace then it would someplace else. Right now it is not rusted through.

If for some reason the Outer Projection/Tube did crack there would be no place for it to go with a long Bolt through it. Meaning the Car will remain driveable.

If Peter Burtons replacement worked so will Mine; Mine will have more meat on it. I think Pete's replacement worked because he measured the length of it so that the Bolt is neither too long or too short.
What would also make a difference is that if an Alignment was done afterwards it might compensate for any extra compresion. Or, of course it might not.

In any event I don't have that spacer issue and now that I am remided about it I am going to do it to both sides. I will try to get to that in a few weeks if I round up the Dril and Tap; I might already have both but I don't know what size the Bolt is.

In the Pic the area with the Green Lines is the Stock Bolt and the area with the Yellow Lines is drilled out empty space.

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84 300D, 82 Volvo 244Gl Diesel