That West Brom away in particular was a cracking result. Memory may be wrong but didn’t we wear red shirts and blue shorts that night? And Peter Ward scored a great solo goal I think, it finished 2-0.
Edit:
https://wearebrighton.com/albiondatabase/when-the-albion-shocked-the-albion-in-1976/
I remember that well. Birmingham were 3-0 up going into injury time and they almost threw it away, but it was 1977 or 78 and a league game, nothing to do with the cup. My Dad was a Blues fan and that was a landmark result at the time - then as you say, 5 years later they lost at home again to...