Have you seen a set that was taken beyond the CNC program? I have not. I figured if they could get 20-25 cfm on the intakes it is possible. Considering the large bore size there could be gains in a larger intake valve. On a 4.375 bore engine you run into issues woth a 2.30 intake valve a little over .800 lift and it has to be pretty well shrouded to keep the chamber from overhanging the bore. Not the case at 4.500".
Have you worked on a set of 270s? I have only looked at pictures myself.
I would be looking for a set of -13s or B1s that already have coated Ti valves and a Jesel setup. You could easily spend 15k on the top end buying it all new. Just one guys opinion based on your goals. It will be a mean package with the 270s.