Reverse EPR
To BOAC,
EPR at full reverse seems to be approximately 1.05.
Number seems not very high, but EPR measurement is apparently not very realistic in the disturbed flow situation during reverse application.
EPR at idle, either forward or reverse would be about 1.00
The 1.05 I have gathered from QAR data readouts of a couple of my own landings.
A better indication of engine output during reverse would be N1, but to tell you the truth, I have never checked those numbers. I just hear the noise and feel the deceleration, and look out in front to judge whether deceleration satisfies me.
The thrust lever angle for full reverse is (-)22.5 degrees, perhaps you can deduce that number from the FDR readout.
EMIT.
(added line about full reverse TLA).