Vacuum Booster or Not?

OK, this is embarrassing. Disregard everything in the last two posts.

I went back out to study the brake light switch problem. Turns out the bracket that holds the switch is adjustable. I must have moved it when I yanked up on the brake pedal to disengage the rod from the master cylinder.

I reinstalled the 72 disc brake master cylinder and verified that the 65 rod will work with this master cylinder.