It is not uncommon for the hemi motors to suck oil into the intake ports due to poor intake seal, one way to identify this is to let the motor idle for 5 to 10 minutes and pull a spark plug(if you have spark plug seals that work ) if there is oil on the plug after idling then it can be the intake seal. Try a thicker, better quality gasket or have the intake machined to make it fit squarely on the heads Have you check the intake fitment without a gasket to see if the space at the top of the intake manifold to the heads is the same at the top and the bottom on all four corners, top and bottom If not you may want to do that, it is not unusual for the intake to not fit properly after the heads are cut and the block decked and so on. Some of the motors from the factory weren't close to being correct