The AC voltage overshoot specifications for Stratix® II devices are shown in Table 5-2 of the Stratix II Device Handbook DC & Switching Characteristics (PDF). Voltages above 4.5V are shown below:
Vin Duty Cycle
These same values apply to the non-transceiver I/O pins of Stratix II GX devices.
Note, Table 5-1 shows the absolute maximum DC input voltage is 4.6V. This is incorrect, the absolute maximum DC voltage is 4.0V which corresponds to the 100% duty cycle condition for overshoot voltages as shown in Table 5-2.