Richard, I've thought about this a couple of times, but never transferred the thoughts to the keyboard...so here you go.
When it comes to A/C it would make sense that engine temperature control will be a problem. The incoming temperature of the radiator will go up when cabin cooling is occurring, which will reduce the radiator capability of rejecting engine heat. So bigger radiators, better fan design, shrouds, higher idles, etc. all make perfect sense.
But from an electrical perspective the single largest load by far is the blower motor. I've measured over the years motors in the 17-20 amp range. This is the largest load in an engine running scenario. The starter of course has much more of a draw but once the starting process is over so is that load. The thing though is that a heater only blower motor and the heater-A/C blower motor is probably no different, or if it is would not be by much. I have not measured both, but can do that at some point. So if we continue with the premise that a blower motor is a blower motor, and since the dampers are vacuum operated, the only additional load for A/C would be the compressor clutch. While these are pretty beefy, I would guess (assume) that they are in the 5A range. I'll have to go measure that now also.
My conclusion is that I see the need for better cooling, but I don't see a need for a heavy duty battery/charging system for A/C.
When it comes to a big block, I suppose that the additional effort needed to turn it over would result in a higher capacity system (alternator/battery) so that multiple start attempts (with failures) in a short duration would be possible. The typical scenario that us over-thinkers talk about is being stopped at a railway crossing, then taking off and stalling out on the tracks. How many cranking events would you want in reserve under those conditions?
To wind this up, the biggest problem with batteries (and recovery after starting) is in extreme cold weather. Someone in Bemidji in winter (-40 degrees, F and C) with a 250 cu in 6 cylinder is going to need more power (with a nod to Tim the tool man) than someone in LA with a 390 in summer. If we had access to the database I would bet that the further north the car was destined, the more heavy duty batteries were ordered.
Let me be clear that my commentary is intended to be a practical discussion of the need, and does not reflect what Ford actually did. For that, as always, we need documentation and untouched examples.