Without seeing it, it's hard to say if it could be restored to "pristine condition" without a fair investment in time and labor (mostly in eventually redoing the finish which would probably be required.). As for returning it to stable playable condition, especially if it has sentimental value to you... and if it has/had a particularly great sound, I would say yes it probably can be repaired and or restored.
Given that undamaged playable Kohno 10s from that era are still being bought and sold for amounts in the $2000+ range, depending on their condition, and because Kohno has always had a bit of "cult" following, it has the basic criteria for what I (as a restorer/collector) might consider "artifact" credentials... (it would "get my attention" on an e - b a y page
The first things I would want to know before even considering bidding on something like this in an auction would be the condition of the neck and the frets, (a more expensive undertakings to restore, and something I would definitely check for wear. If the top showed signs of heavy playing, chances are that the frets would be worn down too... It may sound perverse, but those signs would reassure me that the top probably has GREAT open sound!) I am guessing that this is one of the long scale (665mm) fairly high action models that were the gold standard in the '70s... If that is more of a struggle to play than you are willing to deal with, figure that aspect into your calculations...
If the action and neck set looked OK and the frets and fingerboard were OK, I would next check to see if the crack can be closed with pressure (pressing the sides together gently to see if the crack closes completely and could be re-glued and cleated successfully without gaps). The fact that the back separated near the crack is actually a very good sign... one of the advantages of hide glue is that it is designed to "pop" before damaging anything... if that joint had been stronger, the top might have cracked too. (You can probably thank Mr Kohno for that) If there were significant or uneven shrinkage, requiring a splice... I might have more serious reservations... not because they can't be "fixed", but because that would make me worry more about the intensity of the temperature and humidity stresses that might have caused them, and how they might have effected the rest of the instrument (future problems that have not yet materialized, like loosening of the braces and neck warp)...
In my case, there would also be the intangible "curiosity" and "educational" factor... (what could I learn from Mr Kohno during the repair process by seeing how he resolved construction details, etc.) I have read that he did modify the Spanish designs his are based on, so they would be easier to play for people whose hands were smaller than Segovia's!!
I have seen lots of photographs of them, but have never played one. (I confess... yours has "gotten my attention"!)
Ultimately, it comes down to economics and intangibles... and how far you want to take the process. Would you be happier with a "new" guitar? Or do you want to "invest" in this one? You could start with a relatively simple stabilizing, damage-control repair (using reversible hide glue) and see if there is something really wonderful about the guitar... if you adore it, go ahead and consider having it fully restored. You might have a real gem. (I confess... yours has "gotten my attention", so let me know if you ever decide to sell it!) I would love to see some photographs.