I am not a fan of the seven-tooth steering design, but will admit when they are set up properly (and with extra non-factory machine work as Synchro909 states), they can steer nicely and be a pleasure to drive. You don't get to that point by simply slapping in new parts, though. The basic design has built-in, non-adjustable slop that only worsens as wear sets in. The very fact that Ford changed horses in midstream in early-mid 1929 by replacing this design with the more adjustable two-tooth box says even Henry was de facto admitting that the seven-tooth design had not been as successful as hoped. Making a tooling and supplier change like that in mid-year production of almost 2,000,000 Model A's worldwide in 1929 was a very expensive move that Henry must have felt was justified, as customer and dealer complaints of loose steering mounted up.
When I worked for four (miserable) months in an antique Ford restoration shop in the late 1970's, NOS Model A parts could still be acquired relatively easily. For years most antique Ford vendors sold NOS steering sectors and worm gears that had been turned up by combing through older established Ford dealership parts bins. Replacing these two steering parts was a matter of course when restoring a seven-tooth box that came in a customer's car. More often than not, NOS parts were installed. For show cars, we had to take an extra step to pass judging standards. Even with NOS parts, there was noticeable, disconcerting slop at the steering wheel right off the bat that resulted in deducted judging points. Apparently, the judges back then believed there was to be virtually no steering wheel play - although both the seven-tooth and two-tooth designs call for a little play in the mid-range (neutral, straight ahead). There MUST be some minor play at the mid-position or else the driver would constantly be compensating for the car wandering via the steering wheel. To meet judging standards of the Jimmy Carter era, we (meaning me!) had to apply JB Weld on both sides of the NEW sector teeth and then file/sand them flat while trial fitting for slop. What a pain in the C.K. Yang, believe-you-me!!! Finally, when there was no slop at the steering wheel - after hours of sanding and testing - the seven-tooth box was deemed "show acceptable" by the shop owner. Of course, with time and use, the thin layers of JB Weld wore away and the designed slop returned. But for strictly show car use and limited driving time, it would be a long time before the slop appeared - many trophies later.
Because of this experience, to this day I cringe when I see a seven-tooth steering box that needs to be rebuilt. I can tell you one thing, though - If I rebuild it, no JB Weld is coming within three city blocks of it! The owner will just have to live with a little built-in slop that will only become worse with time and use.
Marshall