First N lines of Body

I don't see an example that helps answer the question:

How do I search the first N lines of the mail body for a regexp?

so before I waste time re-inventing this wheel, I thought I'd ask
here.  I know I'll want to use the scoring mechanism, but beyond
that, I'm too thick to see the solution immediately.

Thanks in advance,
jimo(_at_)eskimo(_dot_)com