Production turbo header. big block A body. any interest?
Space is at a premium on a turbo build, especially a big block A-body.
A simple "log" style exhaust manifold system is usually more than enough to feed hot air into the turbo. The pretty tubes add to the complexity, but not necessarily the power potential. Most people overthink and oversize the hot side. The point is to get hot air moving into the turbo as rapidly as possible. This isn't naturally aspirated and the thought process needs to be different.
Other than planting an idea, I don't have any answers on how to build this type of manifold in a mopar engine compartment, but perhaps this is something to ponder with your fabricator as you start your build.
Over in LSx land, folks will take log manifolds just like these deep into the low 8's@170+.