I got my Scooby Doo on and figured out what the small diaphragm is - it's the diaphragm to the power valve. The carb is now down to the bare body and she was clogged up bad. Lots of debris and garbage in the gallery passing through the throats that joins the fuel bowl from either side. The emulsion galleries were sludged up along with every other air or fuel gallery, and the small check valve in the power valve assembly was jammed from gunk. To top it off the secondary throat was bypassing due to the body of the carb not being true. A half hour of rubbing it back with 400 grit paper and water on a sheet of glass refaced it to an acceptable finish (I did accidentally roll the carb body on one or 2 passes but it only rounded the far outer edge next to 2 of the top cover screws so fingers crossed it should seal ok with the new gasket)

I pulled the main jets and emulsions, soaked them in a citric acid bath and polished them back up. The butterfly shafts are a bit on the worn out side but should be serviceable with a blast of white lithium spray. The linkages and shafts aren't moving freely so the lithium should stop the binding and protect the metal from future wear. I cleaned up a few small sharp edges in the main venturis and polished them up. Last job on my list is to clean the auxilliary venturis up and have a shot at reassembling this thing.
If it's a fail I'll have a nice paperweight to add to my collection