I had this same issue and I just rigged the ring on the beseler to fit it. Mine was a colour head, so I'm not sure if yours will work, but I imagine they all have a collar. If you have a screwdriver, I'm sure you can figure it out.
I'm confident I could probably rig something however I hesitate to make any alterations either to the head or the enlarger body. The adapter rings are out there and may have even been originally included with the head. I need/want one and am not in a huge hurry. BB