Not sure why I was reading this thread as I'm a Kiss diver, but nice set of photos!
One word of warning re the dust caps: I got some which look just like yours (from Beaver I think), they have an O-ring inside and look like they will seal. I got back from a trip where I'd hired cylinders, screwed the dust caps on my 1st stages, and chucked the unit in my rinse tank for a few hours with the rest of it sealed up. Result 1 flooded 1st stage! The ones I have do NOT make a seal
As you have an O-ring on the 1st stage you want a nice flat mating surface in the cap with a centre depression to make a good seal.
Neil
Very good point. But I'm aware of that. I never soak my kit unless the first stages are charged with a tank. I use those caps so they don't fall off and their almost water / air tight. Good point any way.