68' C10 Aftermarket Wheels Backspace

[Chevyswb70]

Hey guys and gals! I haven't posted here in quite sometime. I'm looking to get some information from the gurus or folks that know on wheel backspacing. It's a 68' C10 SWB with a 4/6 drop and front big wilwood brake kit. No other mods. I'm in the process of ordering 22x8.5'' front and 22x12'' rear wheels. And have no clue, on what backspacing to go with. Can someone shed some light on the most functional backspace to go with? I've done basic research, watched a few videos, and haven't gotten too far. Thanks in Advance.