From the internet:
As a guy who worked in a HOJO's in the mid-60's I remember the menu items fairly well. The sandwich you referred to was the Clam Roll. It used the same roll as was used for the hot dog(Franfurt) and the Lobster Roll. It was that type of roll that made the New England 'style' Hot Dog a step above (IMHO) those of other locations where the "normal" bun is the holder of the Dog. The standard Clam Roll contained 2 oz. of clam strips, dipped in canned milk and the flower/batter/breading then deep-fried The roll was buttered on the outside then grilled while the clams were being prepared...so all was toasty hot when combined and served (we hoped!) Price in 1963 was 75 cents.
For me the ice cream of choice was "Buttercrunch" with "Burgandy Cherry" running a close second. Mocha Walnut was another favorite, but it never was a big seller.
I loved unloading the weekly truck. We'd sneak a few bites of ice cream as we worked. All we'd need is a tub and a few big kitchen ladles. Man that ice cream was hard as a rock so we'd chisel with the it out and eat the chunks by hand.
I was a dishwasher, then graduated to cook. The trick in making clam rolls was to never overcook the clams. As soon as they floated up, out they'd come. I miss the buns you mention. They were much better than the rounded ones. Anyway, I still have my first paycheck stub. I made $21.20!