Well this is a most interesting thread and touches on the origins of the second style of chassis used on the Cobra. First off can we dispense with this 'worm and sector' description: I believe the Ford Model A (and others) used a steering box that could be described as worm and sector. In any event this incorrect description of the Bishop 'box seems to come from over the pond and is, perhaps, just a carry over from common usage there? Bishop used a system which they described as Cam and Peg and whilst I agree that their cam is in the form of a worm there is no sector, only a peg. So it is Cam and Peg to be absolutely correct - worm and peg if you must.
As Robin says the system at Thames Ditton was pretty well organised and the whole stores empire, run by old hands like Doug Taylor, did not go in for 'parts bin' engineering any more than did the drawing office. You have to remember how unusual A.C. were at that time: They were a big manufacturer grown small - the opposite progress to marques like TVR or Lotus. A.C. still had all the systems you might find at a Ford or a Jaguar works. So when a steering box, or a steering rack, or a door handle was needed a supply would be negotiated from the likes of Bishop, or Cam Gears, or Wilmott Breeden. The designers and engineers, like Alan Turner, did not look around other car makers parts bins for useful bits and pieces which might do. They obtained specified items from the specialist suppliers and designed them in to their cars. Those specified parts might also be sold, by the parts supplier, to another manufacturer, but as many have found to their cost the A.C. specified part might be different, in essential particulars, from batches produced for other customers.
The whole question of how Alan Turner revised the Ace 2.6 into the Ace 3.6, subsequently named Cobra, is at the heart of this discussion. It seems clear to me that the short timescales which applied put a deal of pressure on the engineering and therefore A.C. did the job in two 'bites.' Broadly speaking the Ace 2.6 got a new back half, pdq, which went straight into production with the briefest of testing (omitting the ill advised and Shelby inspired inboard rear brakes.) It is informative to work on one of these early cars. The contrast between the sturdy simplicity of the rear hub, upright and wishbone and the fussy detail of the fabricated parts making up the front equivalents is a good lesson in engineering. It is blindingly obvious that two designers have been at work - Turner and Tojeiro. A short time later the front half got replaced in a style matching the earlier back half. Beginning to sound like a Pantomime Horse. Anyway I believe this was as soon as Alan Turner had completed the design. The idea that the rack and pinion is the only change is a bit wide of the mark. The whole suspension upright and wishbone, wishbone mounts, hubs,discs, calipers, steering and steering column is changed. It is a major redesign of the Ace 2.6 front end, not just the modification to incorporate a rack and pinion. Just producing the steel cast front uprights to replace the entirely different fabricated Ace uprights would need some significant lead time. I find it implausible that the front half design resulted from early competition feed back - no doubt that feedback occurred, but surely Alan Turner was already well advanced in working up the completion of the front half design? He had completed the Greyhound project and done some work on LM5000 in 1958 and 1959, both machines having coil springs all round and rack and pinion steering.
It has always intrigued me exactly how CS2030 fitted in to this sequence. The time scale fits with the need for a test vehicle for the second Cobra chassis configuration. It would be unheard of for Thames Ditton to put such a radical alteration in to production with no testing and such testing would take a little while would it not? Once completed and accepted then the new chassis could be productionised - new jigs produced, pattern work completed and foundry work set in hand. In those days A.C. could work at amazing speed, free from the parasitic drag of modern institutions like our beloved HSE or VOSA, but not so fast that this kind of change to an existing production line could happen without a development period.
I remember being told by Jock Wright and Fred Larimore, in period, that 2030 was a development car. I suppose that Thames Ditton would hardly be able to justify a 'demonstrator' to Shelby or Ford given that no early Cobras were sold in the home market. So if either of them picked up the bill for 2030 maybe this was the real reason? I have never looked 2030 over and so my post might well be be misleading, but I wonder if in fact 2030 was the 'mule' for the second Cobra chassis design ?