From memory the LM290X series are bipolar input and do not suffer from phase reversal, so the output would be high. The scenario you describe with the inputs being at drastically different voltages can only happen if the amplifier is over-driven so the feedback loop can't close. If this is because you are using the device as a comparitor then I suggest you use a comparitor. If you want your system to perform when both inputs are above 3.5V then there are plenty of more modern 'rail to rail input' opamps to chose from.
