Kevins,
Do you have any
oil mist on your valve cover around the breather cap or PCV Valve? And is there any way that you can run a hose from the breather cap to your air cleaner to let it pull part of the pressure into it? I have had several big blocks and none of them have ever pushed the dipstick out of the tube. And if you made sure that the dipstick wasn't hitting the bottom of the pan, then it almost has to be a pressure situation unless your dipstick is so loose that the vibration of the engine can make it back out some.
Ron