Couldn't get a 741 OPAMP to work as inverting amplifier with smaller (but not so small) resistors
The closed loop output resistance should be very low, less than 1 ohm. 75 ohms is more-or-less what you'd expect for AC output impedance. 

The output resistance is only low for currents that the op-amp can supply. It will go into limiting mode if the output current exceeds a couple tens of mA roughly. It also cannot drive close to the rails with a heavy load. With a 2K load it typically can get within a couple volts of the rails, but is not guaranteed to do better than 5V, so if your supplies are +/-10V your maximum input signal with a 2K feedback resistor and 660 ohm Rin your maximum input voltage would be about +/-1.6V, and with 1K about +/-800mV. It will be less if your supplies are lower.