Yes, the big pantograph on the Hendrich GG1 appears to be attached with one machine screw at the center:
By contrast, the McCoy pantograph on the E2 is not held on by any screw: it "pops" into place and is removable without tools. There are four holes in the roof superstructure into which a pin on each corner of the pantograph pushes (these are not plastic, they appear to me to be stainless steel, same as the pantograph base): at the same time, there is a central boss that is fixed to the roof and protrudes up into the pantograph. To seat the pantograph, you have to line up the four corner pins in their holes, and then "pop" the center of the pantograph down over the protruding stud. There is a spring mechanism in the bottom of the pantograph that "latches" onto a detent on the stud:
Interestingly, the CMC loco used the McCoy pantograph but used a different attachment method, by removing the McCoy pin "insulators", running a machine screw down through the pantograph legs at each corner and through the roof, with a new spacer "insulator", with nuts on the under side of the roof. There is no center boss:
As an aside, the JAD GG1 from around the same period, also uses the McCoy pantograph, and it appears to attach the same way that McCoy used on the E2.
In operation, the McCoy pantograph has a spring which snaps the pantograph closed when it is pushed down and goes "over cam." The larger Hendrich (which I believe is also your Richart) pantograph has a couple of brass clips to hold the pantograph down. These are bent on my Hendrich GG1 and I have messed with them but can't get them working well to hold the pantograph down.
The big pantograph on the Hendrich/Richart measures 2-1/2" high (from the roof) when raised and 4-1/4" long when all the way down. The McCoy is 2-3/8" high when fully raised but only 3" long front to back when closed. These compare to the Lionel 408 pantograph which stands 1-3/4" tall when up, and is 2-1/2" long when down. This Lionel pantograph is also the one used on the Super 381. It would be too small for the Brute.
The Hendrich/Richart pantograph is the largest and would be the best fit for the Brute. But the McCoy with its "over cam" mechanism is the more user-friendly, and at this point probably easier to obtain.
I do not know who made the pantograph used on the Hendrichs (Roberts Lines) and Richart locos. Arno may know.