Switched spindles and now there is interference

I had the same issue. My LCA were the earlier style with tabs outbd. I had a later 73 up sway bar, DC BB k frame. I purchased 73 up LCAs to match the k frame and sway bar. The earlier LCA ball joint bolt hit the outside vertical reinforcement on the sway bar tab. I don't know if you may be able to cut some of the vertical leg and maybe gusset it diagonally or not. From what I recall it hit lower on the tab leg. I didn't have it aligned and it may be a thing of the stop hitting On the other wheel before that bolt contacts if it's aligned.