Sorry to say, but those are not sport seats or sport seat back rests. I suspect they are from an early 80s 911 but possibly also a 944 of the same vintage..
When you are saying piping, you're referring to the thin cord like piece that's sewn into the seam up the edge of the seat back, up over the head rest and back down the other side? And then again around the perimeter of the base? That's piping and it looks perfectly normal to me on your seats.
The cloth pinstripe type upholstery isn't all that common, but again, not terribly odd. Typically it wouldn't continue up into the head rest and would usually be the vinyl there.
The same pinstripe cloth upholstery and red piping, mid-80s I believe:
Same seats and upholstery pattern as yours, different colour in an '83 SC:
Early 80s sport seats, ivory with black piping in an 83 SC:
Late 80s port seats have a far more pronounced rounded profile bolster on the seat bottom and back:
