AM26LS32AC: what's the highest frequency could be input to AM26LS32ACPWR?

Hi Team

The customer have a question about what's the highest frequency could be input to AM26LS32ACPWR?

My customer is planning to use AM26LS32ACPWR for the circuit below.

Square wave from external interface connector will be input to A,B pin of AM26LS32ACPWR first,

then be output from Y pin of AM26LS32ACPWR to the input (B pin) of bus transceiver(SN74LVC245A), 

finally, signal output from A pin of bus transceiver(SN74LVC245A) will be input to FPGA to control. 

The square wave input to A,B pin of AM26LS32ACPWR will be the same frequency but having 1/4 cycle gap between A,B pin. 

For now, the circuit is expected to have 136kHz square wave input, but finally it will have a chance to need to input more than 512kHz signal. 

AM26LS32ACPWR will be driven by 5V, G pin fixed to 5V, G(bar) pin fixed to GND.

After referring to the datasheet, there's only the information about tPLH and tPHL, but nothing about the highest frequency that can be input to AM26LS32ACPWR.

Is there any limitation for the input frequency?

Thanks.