ID --> manual shift gearbox with ordinary clutch. ('68 DS Pallas was last I owned) Pity if this is a US-model. Then you get shitty '68 rulez and ugly headlights. If it's EURO: with the acrylic covers, steerable small halogens on hi-beam, etc. Buy It!)
Big Q - how the hydraulics have been maintained == regular (annual or so) change of std. brake fluid reservoir. Again.. if it's EURO: Steal. It. That would mean mineral-based fluid, different seals everywhere, of course -- better lube qualities over {ugh} brake fluid, thus fewer problems.
(Because the brakes were part of the many functions of the hydraulic central circulating system, in anal-US - they had to use the RED seals and build for our rulez. Mineral systems have Green color-coded seals.) But I'd suppose that the miineral-based system would also have the superior lights, unless it was imported and something weird was done to get it passed.
If serious, Google on Citroen Owner's Club - I note there's 20K+ entries. If it hasn't been abused, it'll cruise at 90+, and prolly 26-28 mpg at that speed. Look closely at the cleanliness of fluid on that 2+ gallon fluid reservoir, for a start. Otherwise it's plain vanilla Kettering ign. system = you can FIX the sucker without $20K worth of proprietary diagnostics. (Hell, I'd put a Cap-discharge ignition on; save the points).
I know zippo about current Cit. parts avail. in US, but WTF -- it's worldwide everything now; why I can even find parts for my Cisitalia, Vacheron et Constantine, etc. If it's been Murican-style neglected and abused.. dunno; can't make silk purse, etc. Impractical to replace Every seal, y'know? I think by '68 the ID prolly had the larger rotary hyd. pump and maybe power steering; inboard brakes were superb: big rubber half-orange on floor / no pedal. No need to lift foot, just move off gas and down to brake; saves at least 0.653 sec.
Luck -
moi
PS - Will be in Flagstaff ~ 4/6 then for a couple weeks: Meetcha half-way..
(OK so I don't count very well, either) Bring tools, parts,