If you look at the proper position of the installed slinger it does what it designed to do. It cups over the seal area keeping excess oil from the seal area. New technology seals do not really require it. This is true on the big or small block engines the amount of oil slung around by that slinger's smooth back side is negligible. There is enough oil thrown off the timing chain and oil fog out of the crankcase to keep any fuel pump eccentric or any other parts well lubricated. If they would have truly wanted oil to be thrown to various places by the slinger it would have been ribbed or veined to catch and throw the excess oil.
Put it together and don't worry about it. Some had them from the factory and some didn't. Not a big deal. Had a lot of motors apart and I great many didn't have one and I have never had a problem with a seal leaking with out one.