SN74HCS125: about vin and vo

At 5 V, V_T+ is 3.5 V. So the output might be high, or low, or oscillating, and this can damage the device; see [FAQ] How does a slow or floating input affect a CMOS device?

To convert from 3.3 V to 5 V, use a device with TTL-compatible inputs like the SN74AHCT125 or a level shifter like the SN74LV4T125.