Eureka! I figured it out!
Take the strut loose from the spindle. Use a 3/8" burr on a die grinder and elongate the top hole on the strut (where it bolts to the spindle) towards the inside about 2mm. Then take a grinder
and remove 2mm of metal from the spindle, right to the inside of where the corresponding bolt hole is. Elongating the bolt hole in the strut gives a further range of adjustment, and removing metal from the spindle lets it move closer the strut without any compromise in structural integrity. When finished, I had about 3.5 degrees NEGATIVE camber!
I am interested in some different lower control arms though. Seems like stock 1303 arms are kinda gimpy, and the stronger 1302 arms just flat won't work with Porsche spindles. Let me know how yours turn out
yetibone