In theory you shouldn't find any of the parts beyond repair if you are flying the aircraft now! If they are removed in SVC condition they can be consigned to your stores in that condition tagged by your own engineers. There are people who make a living from parting out aircraft and selling the scrap, then leasing out the components. There are thousands of components in an aircraft so putting a value on these is a major job - I believe the normal practice to to consider the most major parts values (such as engines and gears) and regard this as the value of the ship with the rest of the components being the profit.
Remember to account for the costs of parting out and storage space for the parts. A lot of the case will depend on what price you can get for the aircraft. In today's climate for old types you should be in a strong bargaining position.