It might be worth looking at the 2 parts lists from Stein Dinse. The first is the one for the SP4 and the second is from the Strada (biposto). The SPO being a bit of a blend of Strada mechanicals, with SP4/5 looks.
https://www.stein-dinse.biz/product_...oducts_id=3045
https://www.stein-dinse.biz/product_...oducts_id=4275