The H's and The M's Used A Larger Block (123 Cu In.)
Well most of that I cannot comment on, butt that quote I can. H's were 152cu" and Super H's were 164cu". High altitude pistons were an option and boosted power during sea level ops. Super H's had live hydraulics and a larger carb. Some late H's may have got the live pump as I know a fellow who has a straight H (late S/N) that has no live pump but the drive adapter has the same bolt pattern as a Super without the pump and it is original.