I slotted the drill motor plate today,

transferred hole locations to the mounting plate and drilled and tapped those for 3/8-16 bolts.

There is "just" enough slop in the mounting holes to allow me to set the pinion depth to the flexplate for a very quiet gear mesh.

I also added a piece of angle to the motor plate to control any "rollback" the drill was seeing during startup.

It wasn't much but it was still there so this piece stiffened it up nicely so now there is no movement of the drill when I hit the gas.
This is almost ready to use! A little bit of welding (attaching the quick clamp) and some cleanup grinding and I should be running beads tomorrow.
Thanks for watching!
Mark