Where to get picture tubes?

[Electronic M]

I gotcha.

Though from owning a Zenith porthole I can tell you that to me that pic looks to have good resolution and and looks like a single Zenith Porthole chassis. Those sets had a big chassis; the tuner alone, which was above chassis mounted, on most was the size of an AA5 table radio of the time add in an HV cage and power transformer to that, and there is no doubt in my mind that that whole thing is a standard porthole TV chassis (with some minor modifications obviously).