Thoughts on how to do this again, knowing what I know now.

• The ACE128 is a panel knob, and is not very robust or easy to mount. Brackets drilling and even lathe work.  Also the approx 3 degree resolution is a bit course on large applications,
• Better to use an AS600, 12 bits works by magnet. Easy to mount/glue magnet to shaft. Air gap to sensor.
• Replace gear cover panel with circuit board. Sensor in the middle.
• board also has attiny841
• proto board to support these options
• mount L298N module to board via female headers And standoffs - replacable on burnout - reduce spaghetti
• Attiny can drive h-bridge and pwm
• Attiny i2c slave
• As600 i2c slave - option of same bus or separate - jumpers
• Pinouts for motor driver for external control
• Pinouts for serial - bootloader programming etc
• Pinouts for isp
• Pinouts and circuitry for stop switches
• Pinouts for extra pins
• Circuitry for xtal
• Two locations for i2c pullups
• Centralize everything - outer board may need cutting to fit alternate motors