Good use of recycled parts.

The only potential problem I see is that you've used a BBQ regulator between your tank and the demand regulator.
From my searches on the web that is a bad idea. Can't remember why exactly.

Look at  http://www.propane-generators.com/ I think maybe that's one place I saw it.

Maybe you can just remove the guts (diaphram and spring) if you don't have a hose that will go directly from the tank to the generator.

I have used one of their kits on my Honda generator. I also have an Onan 6.5NHD which was factory converted to propane.
I also recently bought a kit for an old Onan 4.0 RV generator that looks a lot like yours. Always good to have a spare (or 2) if you're totally off-grid like we are. I picked this one up for peanuts.