I ran 2:34 on flat big-city course, off of 12 weeks of 80-90 MPW. I ran 2 x 74 for the HM on hilly courses in the buildup. I ran ~16:15 for 5K the summer after. I would have been able to do your K repeats session the year before, but probably not while marathon training. Also ran 72 for the half the year before. I went in aiming for 2:32, was on it at 30K before slowing without dying, if you see what I mean.
Think your overall condition is better than mine was, what you have not done as much is practice running ~18 minute 5K pace, especially at the end of longer runs. Some do fine without this, I struggled with the marathon until I learned to love the MP workouts.
On balance, I'd say that going out in ~76 if conditions are good will feel very comfortable, it'll be harder to start much slower off of your fitness. You'll only find out later in the race if that long run is doing it for you.
Nice body of work, good luck.