Vintage Capacitors - Identification - inventory - usability - testing - repairing existing gear

I recently acquired drawers of an old radio repair technicians parts including capacitors, resistors, etc. I plan on inventorying all of these and then trying to see if I can use them to fix or update my vintage gear.

I am new to repairing stereo electronic gear. I recently bought "Learn Vintage Stereo Repair" Build Your Repair Business From the Ground Up The Way" by Luis G Galvez Copyright 2025 First Edition, with the goal of repairing or learning about this.

My vintage gear:

Heathkit AR-1500A with the walnut cabinet - "Hand built by my father in 1974-1975" - It let the magic smoke out of my left Advent Loudspeaker... (Full restoration required)

2 pairs of Advent Loudspeakers in various states of disrepair - Originally stacked with the Heathkit.

2x Carver Model C-4000 Pre-Amps (Full restoration on one or both required.) - They thump on start up...

2x Carver Magnetic Field Power Amplifiers Model M-1.0t (Full restoration required)

A pair of Carver Audio Black Oak Finish Amazing Loudspeakers. Left speaker needs a ribbon repair.

My questions to the ether:

Do I send the gear in to the experts with the matched vintage caps I have or do I barter for a deal to fix the gear and use these as cost cutters?

How do I test these to see if any of these caps are still any good?

If they are still good, is there value in them, used market, trading?

I am not looking to sell our trade at this time. I am just exploring my options as it is still a bit overwhelming.

I am also looking for a Heathkit Audio Scope AD-1013 Quadraphonic Oscilloscope and Oscillator - "Dad had also hand built one"

Thank you everyone.