Wheel Offsets - drop w/cpp modular spindles

[dlong67]

Hey guys, I'm starting to plan on the drop for my Burb and need some advice on wheel offset. The truck is a 70 model with the wider rearen from 71-72. I'm planning on doing a 3-4 drop using the CPP modular drop spindle in front so I'll get an extra 3/4" reduction in track width per side. I'm planning on going with 20x8 up front, or maybe 9.5 if it might fit. I'd like to run the same wheel in the rear if possible so I could rotate tires. Can anyone recommend an offset/backspacing for this combo? I searched the board and can't find much mention of backspacing when using the modular spindles.