I had an interest in that particular Kirkhan shifter recently also. When I called Kirkham to inquire about it I discovered what I had suspected but needed to confirm. Apparently there were a small number (2?) of them made. One was used in Larry Ellison's billet Cobra and the one in Sandwich's Cobra, that he used on his wedding day.
There was no continuing demand for the shifters and It has been years since those were manufactured. Even when they were manufactured, it appears, they were what most firms might have called proof of concept or engineering prototypes. The pics I had seen of the Ellison shifter and then Sandwich's shifter while similar had small IMO inconsequential differences.
I found a good alternative available from Mike Forte. He calls it his TKO Mid-Shift conversion. Here is a link to it on his site, click here =>
TKO Mid Shift. Mike uses a Pro 5.0 mechanism and CNC's a billet adapter to mount the shifter in the mid-shift position on the TKO. He makes the kit for 3550's and TKO 500/600 cases.
Mike's mid shift location on the TKO allows for a natural straight up and down shifter with a natural positioning at the front edge of the driver's seat. When you are done, the install looks and feels very much like a shifter in a 289 car. Gone is the up and down shifting and it is replaced with a more natural and much more comfortable back and forth shifter movement
I am going up to my race car garage this afternoon to do some work on a new engine build. I have a TKO out on a shop cart with a Forte shifter installed and a homemade shift lever attached but not yet trimmed to proper length. I'll take a few pics and post them up this evening.
BTW the shifter stops on the Pro 5.0 mechanism are functional and quite nice.
Ed