Sorry but I can't see how today's riders, good though they are, can be of the same calibre of those in the World Championship days.  Those guys rode on all sorts of different circuits, by no means all short circuits, and still came out on top.  Add to that they could be riding a complete variety of bikes all in the one day, unlike now when they are all very much the same.  
Today's TT riders are roads specialists and unfortunately are rarely in the top half of the field anywhere else.