OK got through what I have and I think we've come up with the same conclusion based on the evidence available
Three examples showing no bracket attached to the motor mount bolt and the cable appearing to route to the front of the passenger side of the block
Even checked similar engines (H code in this example) to see what the workers were doing there and came up with the same routing. In this case attached to a threaded boss at the passenger side and at the front of the block area
A fairly clear 70 Boss 302 example from a very very early Dearborn car
And a look at a block showing the threaded boss at the front side of a 70 Boss 302 block