First, there are manuals in the Kaiser site:

Most of the enlarger lenses have the M39 thread, so they are kind of standard (at least for 35mm and MF).

Enlarger lenses are inexpensive today, so I would advise you to get a 50/2.8 for 35mm and a 80/5.6 for 6x6 (if you use this format) from Nikon, Rodenstock or Schneider, the 3 big ones in this area.

They may be purchased used (but look for a mint unit) both in the classifieds or at Ebay for about US$ 50 (I've bought two Nikkors, one really mint (was it ever used?) and another almost at this price bracket).

Enjoy your photos,

Jorge O