This is a wonderful mod with amazing nostalgia, I played GT3 alot growing up, so it was a nice feeling for me. However I can't seem to get it to work at all, I've even tried multiple CSP versions V1.60 onwards and I'm not getting any visuals, the settings app works, but not the main app itself.
You can check more details here if you wish - https://www.racedepartment.com/threads/gran-turismo-3-hud.202280/
I'm still in the process of investigating this misbehaviour, but regardless, I hope the thread linked above is of any help.