Yes, this would certainly be naughty under current law, but perhaps not in a legal regime where "all speech is OK!" Note that the overt act need not be committed by the speaker, too.
There's even ambiguity about elements of this in current law. If one were to advocate for the violent overthrow of the government, and begin running training exercises to help people prepare to overthrow the government at some unspecified future date--- it is unclear whether this is protected by the First Amendment. SCOTUS mentioned -- but did not address -- this problem in Stewart v McCoy (2002):
... While the requirement that the consequence be “imminent” is justified with respect to mere advocacy, the same justification does not necessarily adhere to some speech that performs a teaching function. As our cases have long identified, the First Amendment does not prevent restrictions on speech that have “clear support in public danger.” Thomas v. Collins, 323 U.S. 516, 530 (1945). Long range planning of criminal enterprises–which may include oral advice, training exercises, and perhaps the preparation of written materials–involves speech that should not be glibly characterized as mere “advocacy” and certainly may create significant public danger. Our cases have not yet considered whether, and if so to what extent, the First Amendment protects such instructional speech. Our denial of certiorari in this case should not be taken as an endorsement of the reasoning of the Court of Appeals....
> unlimited [...] discussion, planning and coordination
turns into evidence once "intent" and an "overt act" thresholds are crossed, for all involved.
[1] https://criminal.findlaw.com/criminal-charges/conspiracy.htm...