need help, dipstick.

I have a 68GTO, run good, start good, Only one problem?
When I punch the gas oil sometime come out of the dipstick.
as long as i just drive normal its ok, but if you punch it that when the oil come out? What can I do to fix this

Check and replace pcv valve, if the problem still happens you may have to put a breather cap on your valve cover. I had the same problem with a 400 I had in my 65 GTO. Putting the breather on the valve cover kept it from pushing oil out the dipstick, but was only a temperary fix. My problem was an out of round cylinder, that allowed the compression of that cylinder to leak down into the crankcase, and pushed oil out the dipstick tube under full throtle.