Decided to go for it tonight and start on the dirty work of the interior. This will end up taking me several days to get the results close to where I want them but I am pretty happy so far.
I started out laying some German Gray over the entire thing, then painting the dash with some Flat Flesh to simulate the buff interior used in most German armor.
After the paint had somewhat cured, I started throwing down some oil wash over some parts I wanted weathered. The wash consisted of some Van Dyke Brown and white spirits. I applied this over most of the buff parts, without sealing them with Future to stain the paint underneath.
I waited about 10 minutes for the thinner to evaporate and went at it with a swab dampened with spirts, which pulled up some of the paint, just like I wanted. After letting everything settle down a little more, I gave a slight drybrush with GW Chainmail to give the exposed metal look.
To take some of the "pop" out of the metallics, I went over everything again with some Tamiya Weathering Master Rust to bring things together a bit more. Finally, I took a broad flat brush and went in all directions to smooth out all of the transitions.
It got blotchy in a few spots, but I was very happy with the way things turned out as this was only the first go at the weathering, there is a few more steps I need to complete.
Hopefully in a day or two the oils will be dry enough for me to do some color modulation with the oil paints so I can clean up some and seal up this interior to begin on the exterior.