Best boards to harvest vintage blacks are old Wyse boards, any board manufactured before 1994 ha vintage blacks.
Also with vintage blaks there are variations, older like 84-89 and "newer" 90-94.
I tested all types also compared the housings and sliders and logos. The vintage black housing has a smooth finish inside, there are a lot of small details.
Also old blacks are nice, not at smooth as vintage ones but still nice, all my board are built with those and they feel nice, and with some lube I think they will feel even better.
I have also some vintage blacks that I will use for a next board.
Now the famous Nixies, in my oppinion those switches are overated, they are as smooth as any vintage black switch, I have a few and was able to test, aside the cool clear top there is nothing impressing about them. Just like any vintage black switch, nothing more nothing less. But still there is the coolness factor in them