Another problem with turf races at GP is run-ups. I'm new here and not familiar with forum policy about links to other sites, but here goes.
Andy Beyer wrote a couple of articles about the problems with unknown or varying run-up distances. One of them is
HERE. He talks about a 7 1/2 furlong race at GP with a 375 foot run-up, making it longer than a 1m 40yd race.
That article has a link to a previous article by Beyer on the subject.