Hi !
I use a Laborator 1000. So a quite different beast.
I had 2 options :
The first one was to buy the large set of filters and fit them in the filter holder between the lamphouse and the condenser set, keeping them in place with a thick glass plate cut to measures, which I do but find un practical, the other option was to buy a set of under the lesn filter, and a front ring from Cokin sized to my lenses front thread. On the Cokin adapter I put a Cokin Pro filter holder into which I slide the filter. It is a breeze to use, and to switch filters during a printing session.
You can also mount the under the lens Kodak holder to the arm supporting the red filter and use it to hold the filters.
Last but not least, the Agfa contrast filters are said to be useable above OR below the lens. If you find a new set, they are cheaper than the Kodak or Ilford under the lens kit....
You may want to ive a try.