Looking for a spacer for a manfrotto 410 junior head.

Hi, I just bought a 410 junior head and it works wonderfull with my tripod. Problem is I wanted to use it also in the studio together with a cambo ust stand (with U-9 ending). So I tried it this morning and it turns out that the knobs touch the base of the stand ending.

So I basically need some kind of ring spacer to have some more space below the head. I was thinking that maybe the manfrotto "Basic Panoramic Head Adapter" (or anything like that) could work but I was hoping for something more simple without moving parts but I wasn't able to find it anywhere. I basically need a ring (like 2cm height) with a 3/8 thread hole in one side and a 3/8 screw in the other. If anyone does know of where to find such piece I would be very grateful.