Probably a groupset swap at the shop rather than 'late' or bought a bit later and the shop sold the Suntour stuff separately or on another bike.
What's the serial number or first half of it.
I remember the add and conversation on here in ebay watch over this.
I would alter seat and grips to your comfort if needed and take the black tap on the stay off.
Then ride it.
I just assumed, perhaps incorrectly, that it might be a late 1991 as the 1992 model came with a DX groupset (although mine doesn't have thumbies). The bike is boxed up again in the shed at the moment but I'll check the serial number when I get a chance.
The saddle is just a RM branded Turbo so I'm sure it will be fine and I'll see how the grips feel when I can actually ride it
Was thinking about fitting a Maple Leaf Flite I have if the saddle is uncomfortable but it wouldn't be period correct which would be a shame considering the rest of the components perhaps?