Sounds like you you have a pressure problem .
Back in the 70s someone came up with an idea to remove smog from our cities. It entailed adding about a 5 dollar part called the PCV valve,!!!!
I can help you. The first thing I would do is remove the smog tube from the back of your engine and install a PCV valve with a vacuum line to your engine.
This should save you a lot of headaches, especially since you are talking about removing heads!