6/70 240Z Ball Joints

The bottom tube of my 6/70 240Z Macpherson strut has a horizontal plate inside about 3/4” from the bottom opening. Recently purchased new ball joints with larger diameter stud and used later-model steering knuckles fit together well. My problem is that the new stud is about 1/4” longer than the original stud and won't fit inside the strut, interfering with the strut plate. I haven’t cut down the stud of the new ball joint yet because I feared it would be of hardened steel (difficult to cut) and the hole for the cotter pin/castellated nut would fall right in the middle of the cut. Alternatively, I wasn’t sure if drilling a whole through the strut plate would affect the structural integrity of the strut. Has anyone seen this problem and have a fix that’s worked?