Geez! With that kind of slope, you have to be extremely careful to ensure you don't start creating artificial dams that hold runoff, because you could end up with a sizable landslide or serious erosion.
If it were me, I would be looking at a series of stabilizing walls that had perforated PVC French drains dug in behind each wall, backfilled with gravel and then covered with earth. There are several different kinds of interlocking landscape stones out there, each with their own manufacturers requirements for installation, that would be suitable for this, and easy to transport to the site. If you build a series of smaller walls, it would be easier than trying to engineer one big one.
The first problem you have is getting a good solid footing to start out with the first course on. You have to pick your elevation, and excavate it level to stable ground, then add several inches of 3/4" gravel, and use a compactor to pound it down solid. Then you can start your first course, and you're off to the races.
Just be absolutely sure you plan your drainage with one of those turkey-strangler summertime downpours in mind. In a strong thunderstorm, can your drain system handle all of the water that would be cascading down that slope all at once? Water has great momentum once it gets rolling, and it weighs one pound per pint. It's easier to keep it slowed down than to try and stop it once it gets moving.
Interesting problem, and I will look forward to seeing what solution you decide upon.