Depends on where you want your torque curve
stock works for stock rpm range
in general a better valve job and steeper bottom cut and blending the bowls helps flow but does not increase the range much as full porting does
Where is the narrow spot on those heads?
No use making the intake face bigger if already bigger than the pushrod pinch
raising the roof much without raising the floor does not help much unless you can relieve a mismatch with the intake
That head is different and there are threads on it-- google around and find some and report back
I wonder if the usual things like flat face valves and 30 degree seats on half inch lift builds apply