You don't need O-ringed heads, but, it will not hurt you either. What you should have done was just leave the O-rings alone and paid the $100 for Fel-Pro Lockwire headgaskets. Ok, I'll step down now.
Now, since this is no longer an option....I think you will just have to try out different ways to get this to work. Definately get the opinion of a reputable engine shop. They see these types of issues all the time.
To ensure that you don't have intake fit-up issues, I would just get the heads re-O-ringed and considered it a lesson learned.
On the other hand does another .004-.007 really make a difference on intake fit? I'm not sure.
Good luck with your issue.
E