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.