If you run my 1" offset hanger/shackle kit with relocated perches and the stock width E-body rearend, I recommend 10" wheels with 6" of backspacing.
You can also install a '65-'67 B-body spec rearend with 10" wheels and 5" of backspacing. This will bolt in with no modifications.
You can get new 10" Rallye wheels with your choice of backspacing from Specialty Wheels or Wheel Vintiques.
I like the 28/12/15 Mickey Thompson Sportsman S/R. This 28" tall, 12" wide street radial fills out the rear wheel wells nicely.