I found my project bike and I have a question if you have a look at the side cover someone in the past has added a oil return as you can see in red, the other hole with the yellow arrow I assume is a factory hole that has been plugged with someone other then a plug
My engine

Normal SS engine

As you can see from the picture above, the area with the yellow arrows is completely different
From what I have seen none have the oil filler on that side of the engine , the engine number tells me its somewhere around the 1982 mark
But what duke did the engine come from ?