Gordon:
I am a submariner only. I have three and my first one was the Robbe Seawolf about 23 years ago. I rebuilt it to a static diver too, five or six years ago. I choose to use a metering pump and an IV drip bag contained in a box. The box replaced the 6 volt acid battery located in the middle. It sounds like you have your parts ordered so I won't try and sway you unless you want to hear more. Robbe Seawolf, 1 meter long, PVC tube/outer hull, right?
Kinkele