We get German-made terra cotta long toms here, in a range of sizes. Here are the sizes I have on hand, the measurements given in order top inner diameter, bottom outer diameter, and height, all in mm:
top i.d. | bottom o.d. | height | 71 | 50 | 88 | 86 | 60 | 98 | 108 | 76 | 121 | 125 | 67 | 137 | 142 | 100 | 153 |
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I do not know if these are distributed in the US, but I think there's a good chance you can find them if you look around. They're not perhaps as longish as the long toms of yore, but I've never seen anything closer.
In addition, one occasionally chances across plastic rose pots, 153×138×228mm. These are simply taller versions of the standard round "1 gallon" pots a lot of nursery stock is sold in. They are just chance finds, used, and I question whether they are even made any more.
HTH