So max capacity is 61, and the rank 45 ones take up 26 space a piece, which means min/max you can do two tatanora at (26+26) and then leaving the last 9 for one invincible (6) and one bronco (3)

Its possible there may be a rank unlock with visiting all known sectors or something, but ehhhhhhhhh.

Also no luck on V materia, sector 15 brought back savage aim IV