That's looking spectacular SOD! Hope you're thinking about doing his poker machine too.
And no, BGJ is one of those characters where there are literally a couple of pics and that's it, and none that show the head or chest from the front. Doesn't seem like they ever took any good quality ref/merchandising pics of the prop.
There is a pic floating around that shows the prop crew working on EV and a droid that people identify as BGJ (due to the vague head shape and what appears to be the insect-like mandibles at front.) It could be an unfinished 8D8 without the face shell placed over the mechanics - mandibles being the tip of the chin and some mechanics extended outward for installation - but the arm at right does seem to match the specifics of BGJ's arms, but it's kinda blurry.
The upper arm just below the shoulder has what appears to be two large hex plastic plumbing fixtures, which BGJ has, versus a finely ribbed fixture on 8D8. The forearms do not match BGJ, but it's possible the twisted pattern seen on BGJ was a sleeve added later.
The pic on the left is what many believe to be BGJ under construction. If this is BGJ, then BGJ has the same torso as 8D8 - which is what I believe.
I'm not sure where Hasbro got the design for the unique chest they did for their BGJ figure. You can see that the pectoral line is higher on the prop than on the toy (arrows,) and in the same position as 8D8 has. As set out below, I believe BGJ has the same torso as 8D8, not a unique torso.
I believe BGJ's torso/chest is at least 3/4 the same as 8D8's. All the points line up.
The arms/shoudlers on BGJ are 3/4 the same as 8D8. The arrows show where the differences are.
The forearms are different to 8D8, appears to be a slightly twisted looking pattern almost vaguely like chain links.