Yes, I had a very early 750SS myself, but never fully understood the "breather" hump.
I think mine had two hoses coming out of it, but it's a bit hazy now.
Out of interest, which way does the one way valve work on the SS hose?
If there are two hoses as I vaguely recall, then maybe they operate as one in and one out?
What's inside the hump? Any baffling or gauze strainer? Or just empty?
Edit.. This is interesting but doesn't really explain anything.
https://c8software.com.au/shopv2/mor...0-ss/fuel-tank
You can hover over the part number and get a pop up identifying it.