awblain - you might want to do your sums again as the RRPM won't be 200 - I'm not 135 qualified but I suspect it is in the high 300s at normal RRPM.
Whatever your maths tells you, there will be a very rapid decay in Nr if both engines fail in the high hover and the ONLY option is a rapid lowering of the collective lever - this will allow continued flight but only in a downward direction to the scene of the accident.