well, you could try 4" sfx pads ?, did you buy any,there only about $6, but you need to buy the smaller backing plate (aprox $12) these will cut more because of the less surface area, if you used #83 on these i think you will find they will work more effectively, you could also use SSR2.5 (thought to be more aggresive than 83), then move to ssr3 if that didnt work, but i still think the 4" pads are a good idea, i took a deep scratch out of my old 182 using the 4" pads.
some paints like different polishes, and i find that the seat paint is quite hard compared to other paints