'69 Dart rear suspension kit questions (RMS and ControlFreak)

Sorry guys. Haven't been in the garage in a while. House burned down so I've been kinda busy and pre occupied over the last few months.

I was able to easily tuck 255 45 18 rims and tires under my 69 valiant with the rms altercation and street Linx kit.

The rims were off a newer mustang (2012ish). The rear is an 8 3/4 with wilwoods. Could go with something wider in the rear if the rim had an off set. Lots of room on the outer edge but it's tight on the inner well. Was thinking about going with taller tire wall in the back to rake it slightly, maybe a 55