Hey Allan, the car vacuum I use is of very poor quality. Something I found at a thrift store I frequent. In fact I just found a second Identical one a few days ago. I got these for $5 each. I could not imagine trying to vacuum with one but seem to work well for a simple fire.
The last time I tried to run my simple fire I was having trouble getting it to go. Air leaks, it is always air leaks. The hose on the vacume had become brittle and would break as fast as I could tape it up. As Dave said almost anything will work and a piece of radiator hose makes a good thermal break as well as an adapter.
As for the ejector I have no experience with one. Try a search. I think it it was Stephen Abbadessa
Who put up dimensions and such. Maybe on his sight, Northern Self Reliance.
Last time I was in Montana I built a large simple fire for an off grid friend in Wolf Creek.