
This is from a few months before Warwick Farm opened and was probably 'drawn' some time before that and isn't quite correct. For instance, the exit from Creek Corner is not shown as parallel to the straight, which it definitely was, while the second left-hander of the esses isn't as tight as it finished up being. Like I said, that next section ran more or less parallel to the horse track 'chute'.
I was hoping to find a UBD street directory from the sixties or seventies to get a map showing this but it seems that the oldest I have is 1989. If anyone has one, probably as late as 1975, it should show both the horse track and the circuit. It would be on map 88.
Subsequent to the closure of the circuit the AJC have extended that 'chute' right out to cross Hume Straight.
Here is a picture posted by 'Wirra' on the Nostalgia Forum, obviously from a more recent time:

There is also a comment from David Shaw relating to it saying that this 'chute' extension gave the horse racers a couple of extra options for race lengths, which were apparently quite important to them.