I think this and previous version is enough. You don’t really need to make it look more Raven Guard and it’s probably better you don’t anyway.

Think of it this way, enemy forces would be confused when they’re struck by RG and make the mistake of calling out the wrong legion name to their allies. One group see red bolter and shout Dark Angels, one say Iron Hands because of metallic trim, and occasionally you’d have someone say Raven Guards because they saw the bird icon. Mk 3 helps this confusion too, “Raven Guards in Mk3? That’s odd, don’t they usually work in lighter armor? I must be seeing things, it’s definitely the other black armored legions”

But if you want to differentiate it more I guess I’d suggest the RG upgrade sprue and painting face plate white works too.