Brakes and cranks look to be Athena. Not monoplaner brakes, but similar to them.

https://velobase.com/ViewComponent.a...m=117&AbsPos=5

https://velobase.com/ViewComponent.a...8d23f&Enum=115

Hubs are probably Chorus, but missing the oil port clip.

https://www.disraeligears.co.uk/site...e_page_63.html

So I think with a 9 speed spline you can go (Campy) 9, 10 or 11 speeds. You can get indexed 9 speed down tube shifters, but they aren't easy to come by. You can also convert 10 speed indexed bar end shifters to down tube shifters. Friction down tube shifters aren't as fussy though, although 7 speed friction shifters requires a lot of travel to get up to low gear. (Although I have heard you can use a bit of cable liner at the shifter which effectively increases the barrel diameter.)

Another option is to find some 8 speed indexed down tube shifters with three springs and then find a 9 speed insert to swap with the 8.

Best option: find some 8 speed 'dual mode' shifters and use them in friction mode. Then you get all the benefits of friction shifting without needing to pull the lever 180 degrees.

If you go indexed you'll most likely need the rear derailleur to match, friction is a lot more tolerant though.