It will dilute the octane some, but you are not going to be sucking in so much oil that car will break or something as long as you have a working set of PCV valves in the valve covers. Trust us its not a big deal, hook it back up the way it should be and do not worry about it. For example I have the stock PCV setup on a car with full bolt on's and a 125shot of nitrous. Its been like that for coming on 4 years now and its still rocking.

You will be fine.