Just talked to a gunsmith.
He said: They don't make after market trigger groups for 870.
He can smooth/polish/clean up the factory trigger, reducing the pull by a pound or so, and making it break "clean", without creep.
$65
Sounds like a winner, to me. I intend to dedicate this 870 to deer hunting with slugs, and turkey hunting, so a smooth, clean breaking trigger is what I need.