Are you sure the units are right?
35psu = 35ppt = 1.026sg = 53mS/cm
Your 29.6psu = 1.0224sg = 45.972mS/cm
If in fact you do have a PSU of 42.7-43 your SG would be 1.0325 or 63.654mS/cm
From NASA website:
"Practical Salinity Unit
Used to describe the concentration of dissolved salts in water, the UNESCO Practical Salinity Scale of 1978 (PSS78) defines salinity in terms of a conductivity ratio, so it is dimensionless. Salinity was formerly expressed in terms of parts per thousand (ppt) or by weight (parts per thousand or 0/00). That is, a salinity of 35 ppt meant 35 pounds of salt per 1,000 pounds of seawater. Open ocean salinity is generally in the range from 32 to 37."
For all practical purposes, salinity in PSS or PSU has the same numerical value as salinity in ppt.