As mentioned above - had Harcourt St. and Broadstone remained in use in 1966, they would have received two of the names of the executed leaders that were allocated to other stations.
In addition to Dev and Collins, another prominent name associated is Countess Markievicz - she ended up on the anti-treaty side of the Civil War, so she probably presents the same civil war politics dilemma (btw, we have since had public buildings and spaces named after all three of these). But, if you want to continue the 1916 theme and pick a name that would be acceptable to both sides of the Civil War - then I suggest you also think about those who died in the fighting in 1916. The most senior of the rebels to die in the fighting was probably The O'Rahilly, who had tried to stop the Rising going ahead, but still turned out to take part. He died covering the retreat from the GPO - cut down by a machine gun, he was refused medical treatment and left on the street to bleed out despite the rebels' surrender. He lived in Herbert Park, so Harcourt St would be a good candidate for him.
Another prominent death was the pacifist Francis Sheehy-Skeffington, who was arrested while trying to prevent looting and summarily executed.
Now all that being said, if a station was being named in more recent times I think it more likely that the search for names would be broadened out to include literary and civic figures as well, so if your scenario involves a modern day renaming of the two stations you might consider some of those too?