I believe you need
this adapter plate to interface a 9015 to the gearbox. (It says it is for the PG71, but if I remember correctly, it is the same style mounting for the PG27. You will need to get the 11 tooth pinion for it, though, along with some new mounting hardware. (If you need the hardware, you could order
this and just use the 11 tooth pinion instead of the 17 that comes with the kit.)