Originally Posted by survive1990
are you talking decking like this>>?
Use the custom search up top and look up 'lapping'. I've done it for several engines, it can help a lot. I've also used a long flat file and filed the bottom of the head/gasket surface flat before. You lay the file flat and work from corner to corner (diagonally) across the surface. The file will make marks on the high areas. As with lapping, you must be sure the file is flat on the work surface (side to side and front to back). File a bit (working away from me worked best for me), turn it 1/4 turn and repeat. When the entire gasket surface has fine file marks on it you know you have no more high spots. I suspect the light cross-hatched file pattern left behind may also help make a good seal, but that's just speculation on my part.
The same can be done for the jug, after it's removed from the engine.
Make sure you clean everything well afterwards, metal filings are not healthy for the inside of an engine.