I would venture to say it would be a MX 2000 or MX-10 RS model. When you are as deeply involved with Perazzi as Ray is Im sure that there are new/prototype things that he is trying also. I believe there is the new Hi-Tech model available also.In ref. to choke more than likely Wilkinson worked BL's in the fixed variety.
You can always call Ray and ask him too, he is a great guy to do business with and very open with information.