Sizing a back to back J Box

[harborrick]

Ok I have a 4" met going up the building with 4 500kcmil
I have to transition up and over pony wall
Trying to figure best solution for wire bending room
I am sure a back to back lb will not work
So a little guidance please

 

[tkb]

Instead of LBs, would 6"x6"x24" wireways back to back work better?

 

[tkb]

Instead of LBs, would 6"x6"x24" wireways back to back work better?

The wireways would have to be 30" long. I forgot about 6 times between openings.