As the first 747s I flew had GEs, I still prefer using N1s to EPR. A good rule of thumb for the GEs on the approach was 60% plus the middle digit of your weight in tonnes. So at 220 tonnes LW you would use 62% and at 270 tonnes, 67%. Now I fly with Pratts, and it seems to work with those too. But not sure about Rollers. Can anyone say if it's the same?