I don't know. Mopars are not known to be difficult to bleed. The only thing I've ever done, over the years, is to leave the heater hose off which connects to the Tstat, fill until coolant comes out there, then attach the hose and finish. Check heater when warming up. Heater should of course be set for full heat, and as engine warms, the heater should obviously warm at both heater hoses. This indicates flow.
When you can check / adjust water level. There is nothing changed in the magnums which complicates this.
Only other thing I could suggest is maybe Stant has finally become fully chineseoattianated. Maybe buy an OEM dealer supplied stat?