I see two bigger problems than finding the cap. With WSB 5 miles away
you are going to literally be swamped with RF and may not be able to
hear much SW at all. Secondly, hearing ANY SW on a crystal set is kinda
hit and miss in the best of circumstances. The signal needs to be VERY
strong and remember that you'll have very little selectivity.store.

Build a tuned circuit for WSB and use the voltage generated as the power
supply for a transistor amplifier for your SW listening.
You will find info on the web.
Mike