Due to its frequency-dependent penetration depth, eddy current measurements are capable of mapping near-surface residual stress profiles based on the so-called piezoresistivity effect, i.e., the stress-dependence of electric conductivity.  To capture the peak compressive residual stress in moderately shot-peened (Almen 4-8A) nickel-base super alloys, the eddy current inspection frequency has to go as high as 50-80 MHz.  Recently, we have reported the development of a new high-frequency eddy current conductivity measuring system that offers an extended inspection frequency range up to 80 MHz with a single coil.  Unfortunately, spurious self- and stray-capacitance effects render the complex coil impedance variation with lift-off to be more nonlinear, which makes it difficult to achieve accurate apparent eddy current conductivity (AECC) measurements with the standard four-point linear interpolation method beyond 25 MHz.  In other words, the coil becomes excessively sensitive to lift-off uncertainties.  In this presentation, we will report improvements in the coil design that reduce its sensitivity to lift-off variations.  The new design uses a reduced coil size even though that also reduces its absolute impedance and its relative sensitivity to conductivity variations, but it is still sufficient for residual stress assessment.  In addition, we will demonstrate the benefits of implementing a quadratic interpolation scheme together with the reduced lift-off sensitivity of the smaller probe coil to minimize, and, in some cases, eliminate the coil sensitivity to lift-off uncertainties.  These, modifications allow us to do much more robust measurements up to as high as 80 MHz with the required high accuracy.