Personally, I keep fivers as they are anymore
Let's see; my Super Course and my humble Humber are both 2x5. One uses a TDC with very low mileage, and the other an Atom. One is Campy Nuovo Gran Sport, the other Huret Allvit.
I use new production chains.
In the event I need a new freewheel, I'll go NOS vintage (if the price is good), or something brand new from Shimano or Sunrace. I won't buy an IRD.
If I want that extra gear or two (or more), I just ride one of my other bikes.