hi,
I don't have any datasheets for those vibrators, but here is my 2 cent reasoning...
In one of my trucks (50 1 ton) the factory radio is using an original type vibrator, likely an Aerovox A-100 or Cornell-Dublier C-00 or Radiart 5300, i forget which, but those should be interchangeable parts.
The radio draws about 4 - 5 amps at 6.3V, about 1.6 of those amps is going into tube heaters, that leaves about 2.4 - 3.4 amps into the vibrator.
The vibrator was a common failure mode in the radio, it could be a little as months to needing a new one, but usually measured in a few years.
If you want your design to last similar to the radio service life of the 1950s i would stick to the conservative limit of 2-3 amps through the vibrator (4-5 amps at start up for 30 seconds while tubes warm up is fine).
But... if your design is easy to get to (for replacement purposes) and you put a big heat sink or fan on it you could probably push it to 2x or 3x from what my radio gets out of them.
My immediate concern would be self heating under load, if you want to push your luck, put a temperature probe on it and make sure you are comfortable with the results.
-s
