516 closed chamber heads on 440ci

hello there and thankyou for all the input, really appreciated! trying to find somone over here who can work on iron heads leave alone somone who knows what they are doing seems to be as rare as rocking horse s@@t. im 50/50 on buying brand new ali heads so i know i got somthing that will work and will save weight,what i was initially looking for was not to disturb my block/pistons and bolt on <yes i know have to find comp ratio on mine.>as it stands would these 516 heads with bigger exhaust valve and some porting work be more benificial than a set or ported 906 on my low comp ?