what would be better set of heads for a 355.motor has flat top pistons with the 4 valve relieves.the motor has a set of 993 cast 194/150 valves,ported andpolished and shaved on it now.i also a set of HO305 heads i was going to use on another motor.they are 416 cast,shaved .10,intake drilled to .194 .150 exh manley budget valves,ported and polished.the 993s is a 76cc and the 416s is 58 or 62cc.all of my sources are saying two diffferent cc chambers for the 416 (305)heads. i know if i go to the smaller cc heads i would get more compression. it will probably put me where i need to mix my gas.the only reason why i was thinking of doing this is because i already have the other heads. i do not know if the intake runners are going to hurt the air flow on the 416s vs the 993s even if they are ported? any advise would be helpful. thanks

 

I would go with the double hump 305 heads, should give you a bit of a power boost.