Don't forget the G&C hll has a growth out to 80 cells. Having the ability to fire and control SM-2 or SM-3 would require the full aegis system, in other words an AWD.
The follow on frigate would probably be sufficient with systems like CEAFAR and associated FCS rather than SPY1D and aegis. This would allow the top hamper to be cut down by setting the bridge down and puting the CEAFAR above it.
The additional cells could be retained and employed for SM-6 (which should be compatible with a non aegis system being fire and forget, TLAMs (if we ever get them), ASROC as suggested (if ever put in the load out) as well as ESSM. It also gives you the option of SM-2 storage for on command launch by the AWD.
The hull size also permit the adoption of a much more comprehesive self defence system for litorial operations and perhaps something like the 155mm AGS.
To clarify, Aegis (or equivlent system) is necessary for SM-3 (to be confirmed for other systems as I though only the most recent iteration of Aegis had this capability at present). For the AAW role Aegis,or equivlent system, provides the mangement of any engagement while the frigates can provide support, including on command lauch of SM-2 if they are so fitted.
1 to 2 sound fine in such a situation, especially if you have an AEW asset (helo based perhaps) allow weapons such as SM-6 to be utilised by the frigate.
In the Australian context a task group with an LHD (or two), two AWD and two 'frigates' (each with up to 80 cells) would have a credible capability (better still of the LHD has its own Mk 41 launcher, system and ESSM).