shame , it could be worse though - you could be modelling N gauge - Dapols attempt is no better.
I fear that the fact we are seeing a real life plastic pre production model basically means most of the metal has been cut now - little things can be tweaked yes, but I think its beyond the point where major shape errors can be corrected (be nice to be proved wrong though) It does seem like the class 60 and 52 all over again.
Here, by the way is what a 50 should look like: http://www.rmweb.co.uk/community/index.php?/topic/112640-trethosa/page-2 it may be a 4mm scale model but more usefully, the corrections to the RTR model give a good guide/explanation to getting the cab looking right. Heljan and Dapol would do well to have a read of that thread very carefully - its brilliant.
Jon