Some Quigley IFS vans have an optional 3" lift. Yours looks like it does not have the lift and should be slightly higher than a 2wd van. Where do the tires rub? You might me able to crank up the torsion bars or slot the bumper mounting holes to slide it forward.
I have a 2003 Quigley savanna with the tiny stock tires. I hoping to run 255/85/16 tires with a small body lift and probably torsion keys and an add a leaf or block in the back.