Tube rectifiers have a limit ... recommended by tube data in RCA manuals. ...
... which is why there is a reservoir capacitance maximum rating recommendation on tube rectifier data sheets.
I only recall seeing a "maximum capacitance" on the
Philips GZ34 data sheet (see Page 3). Everyone else (including every RCA sheet I recall seeing) simply provides an "example condition" (often with much lower capacitance than we would typically use today).
The issue is Peak Plate Current in the rectifier: there is a maximum peak plate current listed, above which you may damage the tube.
The issue is "
Capacitive Current" which is drawn to cause a change of voltage across a cap in a unit of time. More µFs or More Volts or Less Time, and that charging current goes up.
So American rectifier data sheets often mention an amount of "series resistance per plate" (Rating Chart III on Page 3 of this
G.E. data sheet). Ohm's Law tell you for a given amount of Volts, More Resistance causes Less Current.
So there's a tricky bit of math to figure out if you'll retain a peak plate current lower than the tube's limit, and that has much to do with your desired supply voltage, the µFs of capacitance, how much current the amp pulls from the supply, and how much series resistance (in transformer windings, or in external resistors) are in the amp-design.
The safe move is to look at commercial examples of amps like what you plan to build, and don't exceed what they're using (unless there are chokes/resistors in the way).