but! roughly
the same voltages and capacitances are contained in a volume
abt 20% of the originals, what happens with heat dissipation,
are modern cap´s really so lowlossy? Can I use them, don´t
want any explosions in my basement!!
What´s the experts verdict!

The newer types are much more efficient. Most of the gain is due to the
improvements in materials science and chemistry. I haven't any catastrophic
failures in many rebuilds and replacements, but that's not saying it could
never happen. Do be sure to get the polarity right the first time.

The possibility of something going "boom" is always there with old tube gear.
Isn't that what makes it fun? I tell people running a vintage transmitter is a
lot like operating a steam locomotive. You aren't allowed many mistakes.