I'd set the bike up with modern deore LX hubs and derailleurs and use 8 speed cassette, chain, shifters since they are cheaper. You can get 8 speed downtube shifters on ebay for 40$ new. If you want integrated shifter, the high end Shimano ST-R500 might work for your budget but you would have to use cantilever brakes. Some of the alivio cranks are fine for touring and you can save money on the crank and spend it on a better quality bottom bracket for reliability. I would use sun cr-18 rims, they are solid and have been around for years for a reason. I used axiom aluminum racks on tour and wouldn't hesitate to do it again. A generic cartridge headset is fine if installed and set up properly, and so are generic handlebars and basic tektro brakes/levers, a generic seatpost. I would look for a wheelset with plain deore hubs instead of the LX if the budget gets tight, building wheels is usually more expensive... just get any wheelset checked over before you go. All the small parts get pricey too, bar tape, housing, stainless cables, etc. etc.

I think even with careful penny pinching I'd be hard-pressed to do a whole build for under a grand even if I counted my own labour as free (which I never do). Do you have panniers already? They get expensive too...