Remove the motor mount.
Bring the motor in from behind and install the spinner backplate, cutoff prop and spinner.
Put some medium CA glue on the metal tabs of the motor mount.
Bring up the wood motor mount from behind and while holding the spinner aligned to the front of the fuselage....press the wood motor mount in place.
After the glue kicks, remove the spinner, prop and backplate and slide the wood Motor mount and motor out the back.
Mark the motor mount holes in the wood motor mount.
Pop off the motor from the wood motor mount.
Drill holes.
Put it all back together again with Hysol.

Most guys have been using this method for many years and it works very well.