As for using a generic monitor chassis, that would also have to match the proper yoke impedance and then be properly converged and then hopefully have a suitable and stable picture when all is done.
It is really much simpler than that.
For a 19" tube a "generic" chassis should do. Of course you should match yoke impedances, but this is very simple especially for smaller tubes. These guys should be paying me money - go look at
www.jomac.net.auThere would be no convergence problem to speak of, as that is to do with the tube (which we assume works well), and not the chassis.
The very worst case scenario is that you have to go out a buy another small TV for $30, or from the dump, or something.
BTW, international postal rates are very low these days, and it really doesn't cost much at all to send a monitor chassis (ie without the tube).