I think I'm looking for something kind of traditional (not food-wise but Disney-wise). My brother and I went to Disney World for the first time as kids in the 70's but this is only the second time we've been able to work out a trip together as adults and with our own kids. Maybe a more "sentimental" kind of special.
Got it. Boy. That's a tough one. As someone who has visited regularly since the summer of '72, I can tell you that "traditional" and "nostalgia" are hard to come by, as so many places have changed. And lunch narrows the field even more. Since the only 2 resorts open in the 70's were the CR and the Poly, I would have suggested heading there, but you are already having dinner at Ohana and California Grill. Kona isn't really traditional or nostalgic, since it was a coffee shop/breakfast place when you were there in the 70s.
If you are amenable to going into the MK, I would suggest Liberty Tree or Crystal Palace. CP isn't really what it was in the 70's (thank God). No more Chef Boyardee spaghetti or Swanson's TV Dinner "fried" chicken. But the building is the same, and every bit as beautiful. LTT is a holdover from the old days, though the menu is more upscale.
The Grand Floridian Cafe (though not part of your 70's experience) is pretty traditional, both in setting, decor and food. Since the Grand Floridian was really Disney's first major upgrade after the 70's, it might be a treat to make that a place to visit.
I was back there with my bothers (see my avatar picture) for a quick nostalgic trip back in October for a 40th birthday. Just us boys. We hunted around for some of the nostalgia that you might be seeking, and it is hard to find. But that is probably a good thing as the food back in the 70's was horrid. We thought about eating at the Contempo Cafe in honor of all the meals we had at the Grand Canyon Concourse and Pueblo Room. But it just wasn't the same. And Cosmic Ray's isn't the same as when Michael Iceberg used to play his syntheziser. We went to the Cali Grill which we remember fondly (somewhat) as the Top of the World. And we went to Pecos Bill's which never really changes. We had drinks poolside at the Poly. But the best, most nostalgic thing that we did was rent a pontoon boat at the Contemporary for an hour and cruised around the lakes. We buzzed by the old Rivercountry to see what was still there. We crossed the bridge to Seven Seas Lagoon. We used to rent water sprites, or mice, or whatever they have been called over the span of 40 years. But all being on one boat talking and reminiscing was about as good as it gets. Just the four of us on the quiet water with a few water taxis going by every once in a while. If I were you, I would get some picnic food and rent a boat big enough for all of you. (The pontoons will hold all of you). Go out on the water and have a picnic lunch and catch up.