Mopars 1968 '383 Engines'
IIRC, the 335 hp engine had the 440/375 hp head and camshaft. The CR was 0.1 higher than the 330 hp.
I have two different stories on the 290-300 hp 383. One goes that this engine was the 2v long block with a 4v intake. The other goes that it was the 330 hp version that was down rated to keep from triggering insurance surcharges on the A-body. Given the small numbers involved, and the expense of producing 3 different engines, I tend to think that the latter story is more likely. I doubt if anyone would complain about getting less hp than they had paid for.