Early '28 pickup assembly questions

[HHR&R]

I bought a complete unassembled Brookville rpu body to match my chassis and title, I'm assembling it to be as close to an original body as possible despite building a hot rod with some major changes.
So I'm gonna need some infos on some original assembly details, I looked at hundreds of pictures for stuff like number and placement of rivets, but not everything is visible on assembled cars or bare body pictures that people post on their for sale ads.
It's an early '28 frame that will be riveted back, most likely unboxed and an august '28 stamped gas tank. I wan't to keep the early '28 theme on the body assembly.


First question is were all cab rivets waffled on their back side?


I'm missing the frame bracket for the E-brake on the left side of the frame, does anybody have a picture of it to see if I can reproduce one or know what I'm looking for if I need to find one? I didn't see anybody repoping them.


For the bed I don't know what's missing on the front mounting point and couldn't find any picture showing this part from above or under how does it attach to the frame?:
Although I can't remember if I used the bolt hole to bolt my X member I'm pretty sure there's some kind of spacer.


Those are my first questions, more will come as I progress.
For now I'm mocking up everything with metric nuts and bolts, once everything will be where it needs to, they will all be replaced with rivets and imperial hardware (which is a giant pain to find in the EU especially at a reasonnable cost).