Shoot. Try it and let us know!
The color is going to be jacked up anyhow, so you might as well mess around and see what happens. Go ahead and try an extreme pull...perhaps 2:30?
When cross processing this way, you are shooting for a neg, so will be able to burn through the dense areas when printing, unlike with a positive. Overexposing will lower the over all contrast and open up your shadows, which is why some people like to do it with cross processing. Shadows tend to go pitch black with normal exposure. Personally, I like it, and it is one of the main reasons I have done cross processing, but overexposing is a good trick if you want a *more* "normal" look in the shadows.
Each film reacts differently, too. My favorite is Provia 100F, but everything works.