witch are the best flowing 273 heads#

need an opinion or fact wich 273 heads flowthe best stock
I have the 2465315 I think are the # or the 920 or are they like a X vs J 2.02 head I have a set for sale they are camano heads but another guy wants to buy a set but was told the 920 flowed better is there a difference 65 273 head flo head men or motor builders can you help us