Hubs, drive flanges and Wheel backspacing

[Zombie]

For example, a full with 79 ford Dana 60.
The goal being to keep the locking hubs even with the outside edge of the metal wheel. What backspacing would be needed for an 8" wide wheel?
I'm aware that a drive flange can be left flapping in the breeze, but what would the required backspacing be to keep the flange even with the outside edge of the wheel?

 

[78mitsu]

An easy way to calculate maximum backspacing is take the distance from the outermost point of the hub to the mounting flange and subtract it from your rim width, that is the maximum backspacing you should have on that rim keeping the hub even with the outside of the rim. from that point you can add backspacing and rim width to any size rim you want, just watch the sheetmetal.