Just found some new info. The regular dial in filters in the CLS 2000 head are actually a little smaller (87x77 mm) than the supplementary filter (87x83). I removed the yellow filter and put it into the supplemenatary filter holder. It turns out that while it is shorter (back to front) by about 6mm than the supplementary filter, it does cover the enitre space below the bulb. I think ic-racer's option of getting a dial in magenta filter and using it in the place of the supplementary filter is looking better especially as I have not yet found a source that would provide a magenta filter with the proper spectral characteristics cut to size.
I also found that Northern Photo in the UK sells the dial in filters for the CLS 2000 at 200 pounds each. I have yet to recieve a response from Jensen Optical.
£200 sounds a bit steep. Have you tried someone like Bock Optronics ?
Found them through Midwest Optical Systems
Thank you. I'll follow that up.
Just for closure, I have completed my modification of the CLS2000 head. I purchased a complete set of dichroic and UV filters for the head at $200. This gives me some spares just in case. I put the magenta filter in the slot for the supplementary holder. Now split grading is as easy as can be. Now I dial in my starting filtration with yellow and magenta (somewhere between grade 0 and 2), make my soft exposure, set the white light lever to remove the filters from the light path, set the supplementary filter into the light path, and make my hard exposure. Amazingly easier and faster than repeatedly dialing in the filter values. Thanks to all for your advice and comments with this.
Good to see that supplementary filter holder being put to good use in B&W printing. Thanks for sharing your success.
Another thing I did to 'convert' my CLS2000 to B&W was to change the filters over the bulbs that illuminate the dials so they are safe for B&W papers.
I did not consider this. Are the original filters not relatively safe for color materials?