Nothing unusual for the A/C system. Just dismantling our '67 911S targa (light ivory) for restoration and same system was present. It is the dealer installed Delanair system. Always tend to think of the fender mounted condenser as a 912 setup but when first introduced by Delanair for the 911/912 setup, they used the fender mounted version. Don't know if Delanair ever used the front mount or whether this was first used as Behr factory install. Appears in the owners manual. Interesting comment about A/C in 911S. I have not driven a '67 S (as yet) but I understand the have no torque in first gear. This is where the A/C takes its greatest toll as far a power. Would seem to me that nobody would know the difference. I will restore with the A/C, TIG lights, under bumper fogs and screw on headrests as the PO told me they were all part of the car when brand new.
Being old enough to remember these 901 introduction when I was an adult, I also remember that the 356 mentality prevailed at the time. The car was purchased by engineers and pilots as high speed touring cars. Austere comfort was as important as speed when doing six or seven hours on the road (autobahn/autostrada). A/C perfectly logical. How many here go from Boston to Washington or LA to Vegas in an open window Maserati/Porsche/Buick without the A/C on. I think the PO of your car was a progressive. Not an oddball.
