I have a card with a MC74HC125A used to buffer some SPI lines coming from a CY7C68013A USB controller. There are testpoints in place at the output of the buffers. I would like to tap into and supply "my own" SPI signals from an FPGA on another board. There is a latch to remove the power to the CY7C68013A, but there is no way to cut power to the MC74HC125A except for de-soldering and removing it.
Question: Is it possible to drive the lines connected to the outputs of the MC74HC125A with "my own" signals?