I have pretty much the same questions as you and I too have the plans for the generator. I notice that the instructions are quite detailed but contain no photos. Also the Author advises using thread sealing compound on metal to CPVC threaded joints which is NOT recomended (Teflon tape won't deteriorate the CPVC) and he describes a dry home-made flashback arrestor which is never used with Hydrogen gas. Even though these two items make me leary, I'm proceeding with construction with the above mentioned modifications. I have my first basic generator running and it produces a good flame at about ten amps current. I tripped over your post looking for the Beam-Garretson Adaptor and hope you'll share your findings as will I.
I also plan on testing the apparatus on a 6.5Kw generator before I start to butcher the family car.
Good Luck and stay in touch.
John Smith
jrsmith@gnomish.org