I personally would prefer the original 6 if there was a way to do it but if FF didn’t sell I would be gobsmacked if this did. Of the 6: Night Thrasher, Marvel Boy, Kid Nova, Firestar, Nita, and Speedball, I would think the non-negotiable would be: Night Thrasher and Speedball.
Firestar and Nova have the most recognizable names. Both have had figures. If DST added in a cape and blonde hairpiece with mask it would give us a Spitfire. Nova is an easy chop for me and also could be in a future GOTG set. no one is clamoring for that brown Kid Nova costume. That said, ski jacket Miles lives.
Nita is an easy custom. Chopped.
Marvel Boy could be in a GOTG set.
Rage and Silhouette are two fast follow members to the line up that are storyline crucial.
Final Answer;
Night Thrasher, Speedball (with Niles), Firestar (with Spitfire parts), Rage, and Silhouette would be my Boxset with a fast follow GOTG Boxset Of Yondo, Chunky, Marty, Vance (with Marvel Boy parts and Cap Shield) and Starhawk. (With Aleta parts).