Problem is that hardly any V2500 A320 pilot ever looks on the EPR gauge
It's so useless, because difference between min and max EPR lays maybe in a quarter of the gauge. So most of us look at the N1, some on the FF.
Other than that, I would also guess what RRR said in general about the dynamics of a modern jet engine, and I also agree with you that:
- the amber line will fall with alt
- with TOGA thrust you will reach the line
- the EPR limits change with altitude
What the values are - I guess nobody knows, because that's different to atmospheric conditions. If you get hold of an FCOM, maybe you find tables about it?
All the best for your project,
Dani