Damage Calculation Question

I have specific question about a damage calculation involving some newer affixes and support gems. I’m trying to figure out does the skill Eviscerate when supported by Overheat support in conjunction with a way to generate fortification such as the Crushing Reply notable, benefit from the infamous suffix found on helms, “Nearby Enemies take 1% increased Physical Damage per two Fortification on you.”

I’m assuming the damage calculation order based on what I’ve read from the wiki would be during first step of calculating “flat damage” the Overheat support gem is applied during the “added damage” phase, thus consuming the fortification. If at this point the player no longer has any fortification and won’t until the attack hits, then the damage calculation step that applies “modifying damage taken”, which the helmet suffix falls under, would do nothing.

Is there anything I’m missing or is it correct to assume that the helmet suffix won’t increase the damage of the bleed that Eviscerate applies when used with Overheat support. Thanks!