[Jac Mac]

You mentioned that with two breather caps only one spat oil out, are you sure that both rocker covers have similar baffles built into them ( one might have none). I would try a spring or duct tape on the dip stick to prevent it raising up and check to see if the oil leak/stain increases around the breather cap or pcv . If the dip strick contacts a baffle or the oil pickup that might cause it to raise with vibration etc. At least the FE has the dipstick in a suitable place with reference to crank rotation.