That's what I meant. You are not buring off the amount of fuel that was going thru that motor. It has to go someplace and into the pan is the only place to go. It will increase the crank pressure and explain why it is pushing to get out thru the catch can. On the plus side, your oil pan and intake must be sealed very well if it is not trying to push oil out in those 2 places.
On the cam selection, an alky motor will always want to have more exhaust duration to run as efficient as a gas motor.