What is the slowest combo you can think of where you can run a gen-1 hemi? Probably a high-line four-door or wagon with weight added to go one above the natural class. I spent a few minutes on Class Racer Info and found a 1967 Plymouth Belvedere II station wagon 3-seat @ 9.76lb/in that can go into E/S-E/SA (10.00lb/in).
I stopped there. Perhaps there are combos that fit F/S-F/SA or even lower?