Backspacing I'm not sure about. But yes I have 4.5" F and 5.5" R Vintage 190s in silver powdercoat.
Stan, nobody with a Spyder wants 4 x 130 pattern. Nobody.
I've started doing some research on the brakes. There is a local VW bodyman/restorer 3 miles from me. He has a CB wide5 kit on drop spindles lying on his shop floor. He also has a Karmann Ghia with discs. I'm free to measure at will.
It appears to me that MOST of the kits use a spacer on the spindle to push the whole hub out, then have that THICK flange for the studs/wheel bolts.