Even though I have not gotten any replies, I have done some further investigation and can report a solution to the SACD channel reversal problem. The current Chinese digital HDMI to I2S interfaces have a jumper solder pad that causes the channels on SACD only to reverse. This is the OP1 option in the attached picture. The pads are not connected by default and for correct use between an Oppo and GCD need to be bridged. While I used solder I would expect conductive paint will work as well for those not so equipped.
As to my question about pre-emphasis the frequency response with both PCM and SACD is fine. Hope others find this useful.