No, that didn't work for me. First, there is no
F0 F0 F0 at offset 748. I found one at 948, assumed it was a typo in your message. But changing it to
D4 D4 D4 didn't change the dialog color. There are other occurences of F0 F0 F0 and I can try changing them one by one, but that's what I was trying to avoid by asking here