Exhaust smell in cab

So as the title says, I have a lot of exhaust odor in the cab when I drive my 66 GT. I'm pretty sure there's no exhaust leak. So barring that what could I do to try to reduce or better yet eliminate that? What about installing a PCV valve? I'd like to drive her to work from time to time but smelling of oil, gas or exhaust does not bode well when working in an office full of women. ;-)
Thanks for your help