Z 93 was used for Top 40 / AC (John Young could make top 40 appeal to a 20 + females mid days), CHR, IIRC they were Urban during the CHR period too, and Classic Rock, that the Z letter in any station name / brand might be doomed in Atlanta.
IMHO 94-Q has been gone so long that anybody that remembers it is most likely in older demo's that agency buyers are not targeting so it is safe for another station to use Q. I do not see 94.1 giving up Star.
Unless you secure WFOX or KFOX call letters from the FCC (MTM vs WKRP), it would be hard legally to use fox now because of the TV and News Network unless Fox owned them.