Mathematically, the Akerman angle has more to do with the width of the front track. There would be a difference, for example, if the vehicle had a 61-inch front track versus a 69-inch front track.
When it comes to driving conditions, it gets even more complicated, albeit on a more subtle level, when tire characteristics such as sidewall flex and tackiness of the tread to pavement as well as the speed of the vehicle are factored in.
I mention this because
it is possible one may not want a complete adherence to the Akerman angle given the unequal stress taken on by all four tires when cornering. (I'll leave it the racers to opin on what's desireable because I just plain don't know.)
Keep in mind, the rear tires aren't piveting at all (unless someone has instituted four-wheel steering at which point, someone owes us a tech article
).
Even if not perfect, a r&p system allows for the compensation necessary better than a steering box can.
I would think the amount of turning radius per steering wheel turn would be of greater concern. I read on some forum the stock VW r&p system (1975-79) is not as good as the steering box (1971-74) in that regard. If true -- and I have not
yet confirmed this -- this
might be a stronger point of contention when converting and upgrading. (Again, I'll leave this to the racers who would know about desireability.)