Nice set up...I did one similar with a pieces of delrin plastic rod
I bored it deep enough to hold the injector and some Seafoam and attached an air hose fitting and pressure regulator to the other end
I poured some liquid in with zero pressure, pushed the injector in an brought the pressure up to about 20 psi....
I did have to hold it in place and thought about making some kind of keeper for it but it's only gonna be used a few times.
Once the pressure was set, I just used an old MC battery with alligator clips to fire the injector to see if it was clear....two were stuck so I simply reversed them and back flushed....
Whether or not this was correct I don't know, but after I installed them back in the engine, it ran like a champ...
