I've had a lot of success using chipping fluid and will be using it on this project.  I've been experimenting with pre-weathering to provide a range of textures that show through once the chips are applied.  

The whole model was primed with Jenolite Primer Filler.  I've used it for some fdm prints and found it reasonable for the cost.  Then focusing on the tracks, steps and edges I used a very wet "drybrush" building up Rhinox Hide, Mournfang Brown and Wild Rider Red in progressively smaller areas.

The tracks and vents where then masked before applying AK gloss varnish and AK Worn Effects with my airbrush.