HF is ~300baud (it matters that it's baud, because "what's a symbol, really") The faster you send information, the more bandwidth it takes, even if it's morse code. A slow, 6-10 word per minute transmission may be 1-3hz wide, but a skilled operator, even with a clean transmitter will take 30+hz to do 60+WPM. i don't remember the exact number but basically any reference will explain it.
so 1024kbps with the sort of technology that exists in the space right now is basically larger than the spectrum available to us in any band in HF. 128kbit transmitted is probably larger than the spectrum available (you can't transmit past the band edges per license, even if it's "splatter") on all of the HF bands, too.
With multi-level modulation, baud is only half of the story, and the other half is SNR. 300 baud at QAM-4096 is 1.2 Mbps, but you have to have extremely good SNR to use QAM-4096.
SNR + bandwidth goes into a calculation of the Shannon limit of a channel.
so 1024kbps with the sort of technology that exists in the space right now is basically larger than the spectrum available to us in any band in HF. 128kbit transmitted is probably larger than the spectrum available (you can't transmit past the band edges per license, even if it's "splatter") on all of the HF bands, too.