I got a couple of PMs on how I was able to 'lose unsprung weight' with Chrysler-type racing ball joints. Screw-in ball joints use an odd half-height thread and I didn't want to cut down a 1-1/4"-SAE fine tap to reproduce that, so I chucked the new ball joints in a lathe, turned off the threads and used fabricated press-fit metal holders in front.
You could do this with a file, with care to keep the results round. You could also bore out a pair of stock worn-out cast iron ball joints and press in the Chrysler-type ball joints, for a slightly more stock look with stock weight. I tried this and it also works fine.
My more lightly loaded upper holders are 6AL-4V magnesium and the lowers are strong 7075-T-6 aluminum- both considerably lighter than stock cast iron. The position of the upper cross-bolt holes for camber adjustment break thru the holder's big hole and touch the ball joint case, which I relieved to act as positive detents to aid the press fit. I used gr-8 SAE bolts & nuts top and bottom which are slightly smaller but stronger & lighter than stock gr-5 metrics.
The same ball joints in the upper rear (without their threads) shrink-press directly into the Pantera's upper rear arms, with red Lock-tite. Being the type that needs to 'finish' a project, I added 2-1/2" OD holes, sawed in the reinforcing web of the stock upper a-arm for more lost weight. Wheel alignments work as stock and no problems so far (20 yrs & counting). And it's all reversible if you're a purist!