Hi Steamshed,
Re the Saito boiler:
I would hope not much pressure. My boiler has a gauge going to 4 bar. The engine is a triple. 4 bar is 58Lb or so.
If my brass boiler got to that pressure, I would be heading for the hills. It does not normally exceed 2 bar (thank goodness), but, it makes good use of those few psi, it really does. I could send a video if you would like.
Neil.