axle center line to center rear wheels

[fuzzy1nickels]

Quick question that a few of you might know off the top of your head. I am replacing my rear suspension with a 4-bar set up on a rolling chasis (no sheet metal) and I am wanting to know how far back i need to move back the rear axle to center the wheels in the wheel well. I have the original centerline marked, and I was told by a an old hot rodder to scoot it 2" back. Sound right to any one or any one know the exact dimension?

thanks