No, but I think it could work the other way around. My understanding of the necromorph infection is that it operates on an individual cellular level. The host must be totally dead and does not need any specific shape or genetic makeup, while the Flood must have an intact nervous system and sufficient muscle mass which the infection form will abandon in the event that it sustains too much damage. Though I remember there are also Flood "pure forms" which are born without hosts like the infection forms themselves. For example, Flood infection forms are incapable of repurposing smaller creatures like grunts and jackals, while the necromorph infection will take anything from infants to long-dead corpses, and there are a handful of necromorph forms that can continue fighting even after they are blasted apart. In fact, the reason necromorphs must be destroyed in the specific manner of dismemberment is because they have no vitals of any kind, and removing pieces of them is the only way to prevent the tissue rearrangement process that keeps them ambulatory. I'm not sure how the process of a necromorph infecting a Flood form would actually happen, because with living humans it usually involves puncturing the brain which I doubt would work in this instance. Now the real question is what would happen to the collective intelligence that each infection produces? Would the Hive Mind subvert the Gravemind simply by counter-infecting all of its minions? How would the Marker artifact function in this scenario? My theory is that they would gradually begin to meld together into a super-intelligent combined consciousness, which, if still amplified by the power of the Marker, would reach a near-deitic influence.