Replacement for a 74ACQ inverter
Looking at the datasheet for 74ACQ244 https://www.mouser.com/datasheet/2/149/74ACQ244-17733.pdf I would guess that the ACQ part has been specified because the skew (difference in propagation times for different gates on the same device) is low.  This probably won't be critical for the part of the schematic you've shown, but possibly it matters for the other three gates in the device (assuming they are used elsewhere in the circuit).  The datasheet claims that ACQ has quicker propagation times than AC, but in fact the differences appear to be minimal.