Finding the sweet spot for the track voltage and the number of rectifiers needed to get the desired voltage to the motor would be the trick. You should have room in there. The track hot and common aren't that hard to identify. Get some of flex wire. Don't forget to check the smoke unit wires. If they don't come off of the board, they'll need to disconnected.
perhaps one of the AC to DC boards from eBay would be cleaner. Some have a pot to adjust the output voltage.
I didn't see any 6-28660 around, so I see why you went this way. Email gunrunnerjohn for some ideas.
