the problem with your story is you don't have any lap times for LZ14 1600cc cars to compare against, but still claim the 1300cc A series are faster. That's a big assumption. Dino from Speedhunters says he sees it every year at Nismo Festival at Fuji (not in your results) and it's the fastest. Miles faster than Hakos in fact. And the results you post for A series TS Cup racers are slower than Hakos at Fuji...
They were miles faster back in the 70s too - Nissan were tired of getting beaten in TS-a and TS-b (Hako GT-R), so built these LZ Sunny Excellents to try and win outright. On debut they took pole and a 1-2-3 race result ahead of every other car, not just the 1300cc A series you seem to think are unbeatable.