Well I finished the prototype early last month, here is a new screen pass to create a stylized anamorphic bloom for UE, it is not as performant as the UE's bloom and I think I am doing something wrong in the down sample chain, but it does run pretty fast.
Stylized Bloom 1920x1080:
downsample 0.04
bloom 0.06
combined 0.05
UE's bloom 1920x1080:
downsample 0.02
bloom 0.06
I am running in a RTX 2080 super, so it really does not matter, it is fast