Fable is right. The "overangling" situation is one that exists only in Ehrenburg's head. It doesn't happen. He wrote an article which is useful in the sense that includes a lot of details on how to convert to '73+ disks, and threw on his own speculation about the geometry of the FMJ spindles. He never checked it, he didn't verify it, he just said it was bad.
But it's not. Mopar Muscle did a full write up on the swap using FMJ spindles. Not only that, they compared the actual geometry of the FMJ spindles to the 73+ A body spindles. The results? There is a VERY slight change in geometry. One that the average driver will never notice. And if anything, the change in geometry with the FMJ spindles is BENEFICIAL to those running lowered cars with wider tires. Yeah. Here's the article with the actual data.
I use FMJ spindles on both my Challenger and my Duster. Both are substantially lower than stock, both run 275mm wide tires on the front, both have 1.12" torsion bars. All are modifications that would tend to be worse for ball joint life. I've had no issues with ball joints on either.