Will I get a paint chipped look if I spray a base colour let it sit for a few days then spray the top coat and pick at it with crumpled masking tape?

In my experience with the same technique, I would have to say no.
While you'll be able to lift some areas of the paint to achieve that effect, other parts just don't seem to comply. For me, it only seemed to work on the large flat areas, while the places around small details, and especially on sharp edges and around the hatches, it just did not work well at all.
BTW, I used acrylics.

Hi Mike

I haven't tried this , but I imagine it would work best if the top coat isn't given a chance to cure properly...

Like Kencelot says, detailed areas may need a different approach.

Let us know how you get on.

Rowan

I buy a magazine from time to time called modelcraft international. I saw a tip in the last one that might be handy. The guy used a ball of wire pad ... like brillo with all the soap removed. Then he dipped in chip colour paint and sort of using a dry brush method ... used this for creating the paint chips. His model was a 1/16 Kubelwagen and the end result was amazing. With a pulling a dabbing technique he made very convincing and irregular chipping. Definately someting I would consider trying out.... but would try out on scrap first. The kubelwagen was on the front cover .... so it may be worth checking it out if you are interested!