Flat top pistons = More compression provides more power. The stock dished pistons in a stock 302 provide about 7.8:1 compression. If you want more compression, Flat top pistons not only provided the desired compression increase, they also removed sharp edges from the combustion chamber. Since the 302 is prone to detonation, anything you can do to smooth the combustion chamber will help. The estimated compression ratio with Flat-tops is 9.0 or 9.5:1.
paraphrased from a 302-rebuild article
...but I would wait for a 302-expert to respond for more hands-on info
