Rear axle upgrade from SBP to BBP

Guys and Gals ...

I just received my new MOSER 5 X 4.5 axles ... i will be removing the existing MOSER SBP axles and posting them for sale on this site ... as well as compete loaded rear backing plates ( powder coated ) and drums ...
My question is ... has anybody Upgraded to BBP in rear with MOSER axles and what 15 inch STEEL wheel back space fit ( 15X7 ).. I am hoping to fit a drag radial 15 by 9-10 inches wide ...
I will also be sellling 4 ( like new tires ) , 215/70/14 frts and 255/60/15 rears and 4 wheels SBP... Fronts are 14 X 5.5 sbp and rears are 15 X 7 sbp ( Built by Stockton )... all painted T5... THanks