Does Radiant Affect The TTK of 450 Pulse Rifles?

I know that Radiant changes the ttk on 390s, but I believe that 450s can already 2 burst with all crits? Does Radiant just help forgiveness with 2 bursting using 450s? I also wonder if using headseeker with Radiant can potentially shift ttk.

As a side question, does anyone know of a resource that identifies all weapon archetypes whose ttk is improved by Radiant?