I had intended to just fire up the new setup to test to make sure my seals and connections weren't leaking (or if they are, where), and it ended up working so well I was able to fire up the engine! Still a very basic test, with no intermediate gas storage, but very promising!
The last major step to demonstrating a working prototype is connecting the engine to the gear box, and the gear box to the shredder! From there, there are a million upgrades and re-builds I still want to do, but I'm trying to focus on getting a tangible proof-of-concept running in time for the Hackaday Prize deadline! Onward!