X-Head Porting....
The short side radius or short turn is the floor of the port where it makes the turn into the valve seat.
The number one porting gain is the valve job. The best port work in the world won’t fix a bad valve job. Once the VJ is established, any port shaping you do from there out either way has diminishing returns as far as flow goes.
The most important part of shaping the port is one inch either way from the valve job.