When you put the rears up front drill the perches 1 1/2"farther backand it'll move your axle forward a total of 3 1/2"  On th erear just drill the spring perch an inch back and you'll be fine.

Is there any advanage of moving the front forward that extra 1.5 inches?  I won't have to clearance the firewall as much but what about steering.  I still need to mount my IFS box and I've got Marlin's High steer sitting on the bench all ready to go.  Will I run into trouble with the tie rod and drag link hitting each other?  I do like the idea of making the wheelbase as long as I can get it.