[morzh]

John,

Thanks.
Also another effect of jacking up the first filter cap (yes I agree about the second as that one could be ...just about anything reasonable; the datasheet only specifies the first one), even within the specifications, is increase of the output voltage.
So, if one were to increase the value from 50uF to 100uF (and the radio was designed for 50uF value so all the tubes and their operations relied on that) the B+ voltage then would rise and the tubes would operate at unnecessarily high voltage thereby running hotter and having less useful life. Even if we disregard the ill effects of increasing the first cap directly on the rectifier tube.
That also has to be kept in mind.