OEM radius rods can't be adjusted. They use a spacer where the bushing is so it's either torqued down, or it's not. IIRC, only way to adjust OE radius arms is with an aftermarket spherical bushing like the SBMS unit.
I'd say, just use the OE washers. What confuses me is my Avid kit has those large washers too; and it's an aftermarket unit with no large rubber/poly bushing.