There are advantages to a RHD car. For starters, the starter is easy to remove (see what I did there???)
and the choke rod as has been mentioned. A mirror image engine would have been nice and I believe the cost would not have been much more. I think the biggest price difference would have been in setting up the machining operations. Obviously, the exhaust would have run back on the LHS of the car and the location of the battery would have to be changed accordingly. One thing leads to another!
IMO, there is a cheap and easy change they could have made to help. The exhaust manifold could have flowed in the opposite direction and then come down near the timing covers and back under the steering box. I also have a Delage (The Rolls Royce of French cars) and that's how they did it.
One thing that hasn't been mentioned re the difficulties of a RHD Model A is the adjustment of the valves (not that they were adjustable originally anyway) To get the manifolds off, the rearmost stud has to come out with the nut and maybe the next one and that can be a real PITA. Other wise, there is no way they will clear the steering column.