Do those straight standoffs really work?
One of my first electric conversions, I used 3/8" aluminum rod, drilled and tapped at each end. One end to the motor mount, one to the firewall. 4 standoffs. First time I started it, it vibrated like crazy even though prop was balanced. I kind of figured the rods were long enough that they were twisting with the torque and snapping back, or something like that.
Turned me off of long standoffs like that, and I need to make a 1 1/2" long motor mount for my own senior tele conversion.