Mine is ancient, but I assume they haven't changed in over 30 years. The base extends back 3.5" from the edge of the bench. It's 4.5" wide. The centers of the holes for the two screws are set back 1.75" from the lip of the bench. OC for the holes is 3.25". Those are all #'s measured with a tape rather than a mike, but I bet they're within 0.1".
BTW- Good choice. They're powerful, and obviously almost indestructible.
I have found that putting a 1/8th” steel plate between the bench-top and the press help to prevent the bench from wearing in the area where the press is mounted. I have 2 presses on my reloading bench, each with a 1/8th” steel plate between the press and the bench top. I traced the base of the press with holes on the steel plate the just drilled the plate and then mounted the press on the bench-top. I f you do this, ensure there is about 2 ½ to 3 inches of steel extending past the press. This will spread the stress of the mechanical work over a larger portion of the bench top and prolong the life of the mounting surface indefinitely. This may seem a little much, but after seeing what happens to an unprotected bench top with heavy brass reforming and bullet swaging it is well worth the effort. I just thought that I would throw this out there for my own 2 cents.
Enjoy the hobby and good luck.