Lowered 71 C-10, Negative Camber Help

[smh292]

I lowered the front of my 71 with the ECE 4" kit (2.5" spindle, 1.5" coil) and I took it to a good alignment shop and they were able to adjust everything except they said that there was not enough adjustment to get the passenger side camber to within the correct range. He suggested I look into installing longer bolts and an offset shaft. Has anyone else come across this or know where I can get an offset shaft? Are the bolts anything special or would I be able to get some longer grade 8 bolts at a hardware store? I just got new tires so I want to get this corrected sooner than later. Any help is greatly appreciated.