Just an update. The original manifold on my A54 was actually copper and not bronze as I had originally thought. That explains the corrosion, since copper is lower on the galvanic scale than bronze, which is the more noble.
I am having a fabricator make up a new heavy-gauge 316 SS assembly with individual shut-off valves and a clean-out connection at the end to allow snaking in the future. Stainless may not be as good as bronze in an anaerobic environment, but I will probably be long gone before it fails I am sure. I thought about the fitting approach which would have allowed disassembly, but the original concept manifold is not that difficult to remove - if I ever have to again. I understand that stainless will likely be a bit heavier than copper, but I can deal with that.
I think others have provided good photos of the manifold, but I will be happy to send out pictures of my final installation if there is any interest in my approach.
Phantom, A54 #44