Converting old amp to IEC power receptacle?

I have an older NAD 906 power amplifier that has an attached power cord. The built-in shelving which I want to put the system has a bunch of the previous owner's IEC cords already run behind the wall, etc. To use one of these, how difficult would it be to install an IEC receptacle in the NAD unit? I gather that since the original power cord was not grounded, that I should leave the ground tab of the IEC receptacle disconnected? Many thanks for any tips.