Good News! It's been tough in my brain trying to find a Space Marine army to play that fit all the criteria that I need:

1. Easy to find Shoulderpads and Emblems for vehicles. Decals or Plastic.

2. Ridiculously easy paint scheme.

3. A Chapter that exists in the official lore, even if it is super obscure.

The Internet has heard my cries and granted me the following:

The Knights of the Raven!

Yep, a Raven Guard successor in shiny metal armor!

The paint scheme seems to be.

1. Spray model with Leadbelcher 

2. Add black details

3. Add leather details

4. Make them 3rd company with red kneepad

5. Wash with Nuln Oil

What do you think?