So Brett- what exactly in your mind is the G-O with that little stumpy lever? The one I have doesn't have a part number on it, and is ~42mm/~1-5/8" between shaft centres?
I've trawled though the few parts lists I have for A7/10's and B series pre-units, and can't see a picture or listing that fits its' description.
Listed as Brake Arm Plunger- '49 -'57; 67-6053 (Long one) ??~68mm/2-11/16" Shaft Centres??
There's some confusion about this, as some are calling the 67-6053 a 'short one', but in the parts lists, it looks longer than the one in your picture (which is like the one I have @ ~42mm/ 1-11/16")
(Brake Lever B31/2/3/4 Rigid & Spr.?49-?54 /Comp) ; 65-6279 (Long ??~68mm/2-11/16" Shaft Centres??)
( ? ? B31/2/3/4 S/A ?54/5/6) 42-6045 (Long ??~68mm/2-11/16" Shaft Centres??)
Personally since I fitted a 40-6041 lever, I've decided that the short one with no mumber is a piece of junk