Plunger spring is at the top of the motor. Just replace both gaskets, refill with oil and you should be good to go. See if the original top sump gasket has a piece missing as you disassemble. There are a few bolts around the oil filters (they live in the dark) that also needs to be found and removed to get the sump off, aside from the ones around the perimeter.
From memory, there are 4 bolts holding the spacer plate on, after the sump comes off. Go slow and careful - should take around 30-40 minutes the first time.