Hi. I'll let Chris comment but I asked him to post the picture to show the excellent machining work in making the plate. He might sell those separately, however.
This motor is 11" in diameter which is a tad large for my donor car. However, forum member azdeltawye
documented how it fit his 11" DC motor in a Jetta (similar to my car) by notching off some of the motor's face plate so that's encouraging. The thought of 80kW peak power is way too temping to not try...