Me, I'd start with a basic black paint job and then start masking off different panels and sections so I could then hit those areas with a different shade or sheen of black. Since you are using spray bombs, you'd need to mask pretty much everything else to avoid overspray.. I think that you could make an interesting paint scheme by varying only the sheen of the paint itself, but again, lots of masking. Tamiya's Nato Black is an awesome color and Model Master/Testor's/PollyScale make a number of different shades of black that can used although I don't know of their availability in cans.
I can't think of what I'd use to preshade a black finish except for varying shades and tones of dark grey.
Sounds like it will be an interesting collection at any rate.