Just get with your local dirt track supply house, or Speedway... They sell a bracket to weld on the housing to use GM metric calipers and rotors on a 9", about $300. You can get everything other then the brackets at most any parts store and do it all yourself for a bit less... The package from Speedway is probably the easiest and quickest way....

I don't like using spacers myself, I'd just get wheels with different width and backspacing to run the bigger tire.

Pinion centered puts the pinion in the center of the car, where it should be, and uses different length axles....