I think this is correct.
4 wires at the plug on the wiper motor:
blue-positive power
blue/white-park ground
blue/red-low speed ground
blue/black-high speed ground
blue/white and blue/red go directly to the motor
3 wire bar:
black, closest to the motor, goes to a screw on housing
blue/black is...
the original rotary switch only had 3 places for wires and the had a post that had a screw in the end to capture the bare wire when it went thru the post.
the wiring you show going to your switch looks like 4 wire flat trailer wire.
does one of them go to ground and the other 3 go to the wiper...
the 75-80 wiper motor should have constant positive power, the stock wiper switch, switches the ground to make the wiper motor work, park, low and hi
the stock 66 had a 1 speed dual motors, park and on using the rotary switch
the switch shown is not a stock 66 switch and the wires are not from...