In theory, if you make a website work with one screen reader, it should work with all of them. Of course, in practice, just as with browsers, there are corner cases where screen readers differ in their support or interpretation of the standards.

My guess is that if you make the site work with either Orca or NVDA (an open-source Windows screen reader), it will work with the other, and with JAWS. So if I were you I wouldn't bother to set up JAWS and test with it.