Did the 340 really make 275hp?

in their day (early 70's)...as I remember (can't believe I'm say'n that)....those small block "pure stockers" in a A body was a great combo. It was only when my buddies tried to "pump it up"....raise compression, massage porting, bigger cams...that they had issues. Primarily.... the 10 bolt heads were the weak point and would give em fits.