Okay, after the Crisis, there was no Legion reboot just a revisionist's history of the Legion's relationship with Superman?
More like a retcon. It was revealed that the Superboy that the Legion had known of since their inception and had had adventures with since 1958 was actually a Superboy from the "pocket" universe; and would never grow up to be Superman.
So, the original Legion survived through the Crisis until Zero Hour or do you consider the revised Legion a soft reboot?
I consider what you are calling a "revised" Legion to still be the same original Legion. Just like the Superman published in the post-Crisis, pre-Byrne Superman titles was still the original Superman. The characters published during and after the PU Superboy's death and immediately after the 5-year gap had the same memories and histories as the characters had since their first appearance. It was all one big continuous story.
In the Beirbaum and Giffen series, there was a single issue where Mon-El died, and in the process of his death, rebooted the entire universe such that Supergirl was replaced with Laurel Gand. He may have erased himself as well. This was a separate and later retcon than the pocket universe Superboy fudge.
This was sort of a half-reboot, half-retcon.
Then there was the Zero Hour reboot where Cosmic Boy was revealed to be the Time Trapper. I think there may have been yet another reboot shortly thereafter that resulted in the recently spun-off SW6 batch becoming the real and only legion, with an all-new new origin; or it may have been the same reboot. My memory is fuzzy on the details.