Bear in mind that the smoother the surfaces, the better the thermal transfer between them will be. If you have the patience and can get 1200, 1500 and 2500 you could take it to a mirror polish:
Although I did not do it, you could then use some brass polish on it. If you do, make sure that you clean the surace very thoroughly with a xylene-based cleaner. A high-percent rubbing alcohol will do. You will know when it is clean as the cloth (white T-shirt works well) will no longer remove any more polish residue. No offense if this is already known to you...
Not trying to be picky, just thorough. I regret not thinking about or having read about the polish thing prior to re-seating.....next time.