...This photo gallery shows us the correct 225mm Fichtel & Sachs Pressure Plate the Porsche factory used in the 911 RSR (later also used in the 934/935). Aside from the obvious lighter Aluminum frame, one other significant difference between this clutch and the "more common others", can be seen in this photo here https://pbase.com/image/56080362 - The street pressure-plates only use a "double-leaf spring" setup (not designed for heavy-duty use and abuse).

If you have one of these pressure-plates available for sale, I am interested in purchasing it and can be contacted at ajserrano@msn.com - Thank you!