CDDA does that, but the codebase is quirky (arguably does what it has to do quite competently, but there are limitations)
look here for the whole codebase, and specifically the monster and mondeath files to undestand the problem. Revivification is handled by the MF_REVIVES tag, so grep for this also.
IIRC items are only spawned on death, and are never part of a monster since a monster class differs from the NPC class in that it has no inventory (not the only difference). I don’t know if implementing all monsters as NPC’s (or even making a new monster class and then creating the NPC class as a subclass from that) is feasible.
Best ask here or raise an issue here to get dev attention.