Okay, we all chimed in with our internet opinions, some very insightful, and some funny. And one that required a dictionary. But there are a couple things that do make it a clearer reason. The largest is the Scripps Factory vs other engines. And from that one thing, one can deduce from the fact that on the Scripts the Carburetor and Water pump are on the Starboard side, and on the other engines, Port. And one thing that was always paramount in a designer and Engineers mind back in the day, was access to these parts. Quick access, since those two parts were most likely the reason for any safety or performance issue. This is the only thing that makes sense. ACCESS!
Like some said, the construction is not any harder from one side or another of the seat design. And therefore, the Scripps versions would have been setup differently for ACCESS. Think about it, back then you would need to add oil to a new engine, and have a deeper relationship with the carburetor than you did with your wife. It’s very normal to tweak stuff depending on the weather and conditions, just a tiny bit here and there.
Now, as an owner of a 25 Sportsman, I can attest to this. The area in the non Companion Way area is a collect all for stuff. Life jackets, a step? General crap. It just finds its self there. And its a bit of a pain to go around there to check on stuff. Like a cracked manifold etc.
So there ya have it, until someone produces a sheet of paper from the factory on this topic. A Change order. And yes we are working on that. We stand tall in our opinion. Now get out there, its gonna be a warm weekend to breakdown and require access.