I have a Marushin upper, bought it for a project but unfortunately I never got round to doing it.
It's only the upper, rear sight assembly, forward assist. No dust cover or det chamber.
It's been coated with Brownells Aluma Hyde (Matt black) epoxy based firearm finish.
I was going to broach a slot to fit a real charging handle and also retro fit a real forward assist.
I have another spare if I ever decide to carry on with the project.
If it is of any interest drop me a pm.
Nick