Spice Transimpedance amplifier AC analysis
One milliamp AC input current yields one volt output voltage when the transimpedance amplifier uses a 1K resistor. The output display scale is "dB" relative to one volt. If you change the display units to "linear", you will get a display near one volt. It will actually be very slightly less, since the op-amp hasn't infinite gain.
The output will also contain a DC offset of 0.21 volt as well, but that doesn't display in "AC analysis" plot - only the AC component and phase are displayed.

You could use LTspice's .MEAS statement for gain calculations. Something like:

.meas AC gain MAX V(Output)/I(I1)


In your case, it should give a result near 60 dB, and shows up in the log file:

gain: MAX(v(Output)/i(i1))=(60dB,-6.36019e-005°) FROM 10 TO 5e+006


gives a display of maximum gain, at any frequency in the display. The measurement function is complex, but can do a lot with a plot file.