I wouldn't compare the LS3's vs aftermarket cathedrals as they will be closer than you think. Drive ability and acceleration wise. We should be comparing A LS7 or larger aftermarket head like a LSX DR. "NAVYBLUE210" seems to have a good grasp.

 

So after the smokes clears which would be quicker on a 440ci motor ? A cnc ported LS3/LS7 head or a 245 plus cc cathedral head ?

 

If those are my only options, The LS7. Not take off LS7's. Something like these
http://www.livernoismotorsports.com/...LS7-HEADS.html