HELP: Spare Parts?

[Dave-In-Maine]

My list (personal preference only, and I do not have everything on this list yet, and it will probably change) is to have on hand at least one of everything that either moves, contains a number of small parts, is known to break, or is small enough to lose very easily. So, my list is:
Complete set of springs, complete set of pins, spare bolt (complete, checked to the rifle and ready to drop in and use), spare bolt "guts" (all the internal parts), spare pawl(s) for the bolt tool.
To be clear, I look at these as parts needed to keep my carbines running, not to maintain "originality," so I am not concerned with them being "correct" for the rifle. If the parts are USGI, I am good to go. For example, a 1950's round bolt is fine for my 1943 Underwood.
Just my 2 cents worth.