The keyway in the pump shaft is slightly offset from the centerline, and sometimes it can be hard to see which way it's offset (it's dark and oily down there). The oil pump gear is has maybe 12 teeth, so it's possible to install it in 12 (if that's the correct number of teeth) different orientations. The key on the base of the distributor shaft is also offset, and it's also able to float back and forth a little bit. So, it's not very hard to push in the distributor 180-degrees off. I think the Bosch distributors are easier to install wrong than the Marelli. Anyway, you really need to have a picture, which I don't have handy, so maybe another member can post one or two for you. It doesn't really matter at all if the pump is installed differently from the spec, as long as you install the distributor correct, relative to the pump, and install the spark plug wires to match.