They did have non power disc brakes available on Ebodys, but not in 1970. I think the non power DB option started in '71 or '72.
The engine compartment shot shows a drum brake style master cylinder. The disc brake one has one fluid chamber that is about 3X the volume of the second fluid chamber. Also the lid is held on by a bail wire. The drum brake master cylinders through 1970 had a bolt on filler cap.