It's a small world Taff. Last week we learned we were both at the Newport v West Ham cup game. I was at the Welsh Cup game you mentioned. That got a bit tasty off the pitch. Cardiff got to the Vetch early and invaded the North Bank. However when the Swans fans turned up in force we ended up being split between the 2 ends. We left the ground "carefully" after. A bit tense going into extra time but I think we were good for the win in the end.
I was at that game as a 14 year old in my normal position at the back of the North Bank standing on the angle iron supports on the back wall. You would get a good view of the pitch and and any 'action' between any visiting supporters who had gone onto the North Bank. I have vague memories of that Cardiff game although I do remember that we lost!