Now you can use a circuit like it's implemented inernally of INA117. This is an instrumentation like amplifier, but which provides a reduction of input voltages, concretely spoken 'common mode input voltage'. An isolation amplifier is no longer necessary, but maybe still usefull. Depends on actual application, which I do not exactly know up to now.

I guess you still need the shunt resistor to sense the current? If you connect the both inputs of INA117 to this shunt, then by design ground noise is suppressed by the common mode rejection ratio of INA117. It depends on your needs, whether this rejection is sufficiant for you or not. Please have a look at datasheet of INA117 and take care, that the shunt must be orders of magnitude smaller than the resistors used internally of INA117 (380kOhm).

Circuitry of INA117 is so simple, that you might think you can do the circuit also with cheap discretes. But, take care, high common mode rejection is only fullfilled with INA117 chip, because precision and matching of internal resistors is unique. Building the same with discretes would mean the need of very very precise resistors, to get the same performance.

The INA117 I suggested to you, because I don't actually know, how high the maximum input voltages can be. If you don't need so much reduction of common mode input voltage, then you can also use INA105 or something similar, of course.

Kai