Maybe 15 years ago, I repaired and semi-restored a fairly beat-up and already-modified BC-455 receiver and
transmitter and set them up for operation as a pair on 40 meter CW. I was making a typical surplus Novice station I suppose.
I wanted to power the transmitter from a Heath HP-23 - so while I was fixing and restoring the transmitter, I also upgraded any components that would not stand the higher PA plate voltage. Knowing the ruggedness of the 1625 tubes, I did not hesitate to exceed their rating. With a transmitting capacitor in series with the output (to a existing SO-239 in the upper left corner of the front panel) the transmitter tuned up normally and I got the 100 watts output you would expect.
Very satisfying results. I treated the 1625s like they were 807s or 6146s, and they did not have a problem handling the extra voltage and power. Of course, bear in mind that tubes of various vintages and manufacturers may vary in how much abuse they can stand, so your results may not be exactly the same as mine.
My approach was to leave the power supply alone and modify the transmitter to accept the voltages if offers. And it worked out most excellently.
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Radio is your best entertainment value.
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Mein Ohr ganz nah am Weltempfänger...