The power lines are quoted as being two sets of three wires carrying 38,000 volts. These lines would be erected at a minimum distance from the ground and away from any horizontal obstructions to avoid the risk of arc over. The power lines would have complied with electrical standards imposed at the time and are unlikely to have been "over engineered".
So it should be possible to establish from the old standards, how thick the cables were, the typical breaking strain, at what height the cables were strung above the ground and the horizontal separation from the railway tracks.
This information may help to indicate the vertical path of the aircraft as it sliced through the power lines and the wing tip contacted the railway embankment. It should at least verify the estimates of a ten degree nose down flight path.
Standards for modern high voltage power lines are probably not too dissimilar to those as the time of the accident since the same laws of physics still apply to power handling and flash over voltages.
For example, in the UK, the minimum height above ground would be in the region of twenty feet. The cable thickness would be at least two inches, or more, depending on the current carrying capability.