What would an acceptable replacement be for a discontinued Motorola HCT174A?
74HCTxxx is a standard logic family (just as 74HCxxx, 74LSxxx, 74ALSxxx, etc.)

All manufacturers were supposed to abide to the same nomenclature, input and output logic levels, fan-in, fan-out, and timing. 

Parts within the same family are supposed to be manufacturer-independent. 

Furthermore, 74HCT parts were designed to interoperate with both 74HC and 74LS parts, to give more freedom to the designer.