Have you measured your clearance from tire to leafspring. I have a Challenger also, and I had to move the leaf springs in (Dr Diff kit) just to gain clearance for 6" backspacing. Rims are on order now, hope to have them soon.
I created a simple spreedsheet to calculate the delta inward and outward for tire/BS combos. All cars must be different because I see Goody running 295's w/6" BS and not moving the springs. Granted he added a spacer, but I can't run that same combo with my springs moved in 1"
Bottom line, measure your set-up and then calculate what will fit.