Was Stanton a murder target?

[RJNorton]

a. The April 10, 1865, letter to Booth, signed T.I.O.S, states that one assassin had been assigned for each member of Lincoln's cabinet.

In Frank Flowers' book on Stanton the conversation between Booth and Coyle is reported somewhat differently than in the article by Messrs Hall and Maione. This is the way the conversation goes in Flowers' book:

Booth: "Coyle, what would happen if Lincoln were removed?"

Coyle: "You would have Andrew Johnson, not so good a man as Lincoln, for president."

Booth: "What if Andrew Johnson, too, were dead?"

Coyle: "The president of the Senate would succeed as president."

Booth: "What if Lincoln, his Cabinet, and all the constitutional successors were out of the way."

Coyle: "You would have anarchy - but what are you talking about? There are no Brutuses in these days."

Booth: "That's so; no Brutuses in these days."

If Flowers is correct on the conversation - I just wonder if Booth incorrectly thought the line of succession included the entire Cabinet, with Seward and Stanton at the head of the list. (?)