Spare Parts
Ken mah fren...If ya put it together with the right parts, ya probably ain't gonna need any spares unless ya carry 25,000 rounds of ammo to the Congo with ya.
Seriously though, old Colt commercial or NOS USGI parts would likely see ya through the storms for years to come unless you try to shoot the gun to destruction year in and year out.
Just to be safe though, I'd want a spare recoil spring plug and a spare plunger assembly. An extra recoil spring wouldn't be a bad idea, as well as a
firing pin spring. Maybe an extra firing pin stop too. A full set of pins
and an extra mag catch assembly, ready to slap in. Magazines! Can't have too many magazines or too much ammo.
For a hard-use beater that'll never see the Congo or the Gobi Desert...all of the above and some things in multiples...a spare extractor, pre-fitted and tuned and ready to rock would be good too. Grip screws and bushings...
maybe an extra plunger tube and ejector...a pre-fit disconnector wouldn't hurt. they usually wear faster than any other part in the fire control group
except the firing pin. A spare trigger too...I've had one to break at the corner of the stirrup. If it had been my only gun at the range, a 45-minute trip would have been wasted. I now carry a spare trigger in my range kit.
A hammer strut too...even though the chances that you'll need it are slim
if you use a good one to start with. If ya can't find a NOS GI strut, and new-style Colt strut is blanked from good steel, heat-treated, and hell-for-stout.